Language:
  
[Sign in] [Register]   

EIAab logo

Index > Protein center > ANGPT1(Gene name) > Human
  • Add your favorite
  • ANGPT1 (Gene name),
  • Angiopoietin-1 (Protein name ),  ANGP1_HUMAN from NCBI database.
  • top
  • Come back to page head.
  • |
  • General Annotation
  • |
  • Antigen Annotation
  • |
  • 3D
  • |
  • Predicted Eptitope
  • |
  • Vaild Sequence
  • |
  • Related Databases
  • |
  • Citations  (1)
  • |
  • Feedback
  • Gene name:
    ANGPT1(KIAA0003);
    Protein name:
    Angiopoietin-1(ANG-1);
    Alternative:

    Organism:
    Human (Homo sapiens). 
    General Annotation
    Sub Unit:
    N/A
    Function:
    Binds and activates TIE2 receptor by inducing its tyrosine phosphorylation. Implicated in endothelial developmental processes later and distinct from that of VEGF. Appears to play a crucial role in mediating reciprocal interactions between the endothelium and surrounding matrix and mesenchyme. Mediates blood vessel maturation/stability. It may play an important role in the heart early development.
    Subcellular Location:
    Secreted
    Protein Attributes:
    Sequence length:
    498
    Sequence:
    50:
    MTVFLSFAFL | AAILTHIGCS | NQRRSPENSG | RRYNRIQHGQ | CAYTFILPEH | 
    100:
    DGNCRESTTD | QYNTNALQRD | APHVEPDFSS | QKLQHLEHVM | ENYTQWLQKL | 
    150:
    ENYIVENMKS | EMAQIQQNAV | QNHTATMLEI | GTSLLSQTAE | QTRKLTDVET | 
    200:
    QVLNQTSRLE | IQLLENSLST | YKLEKQLLQQ | TNEILKIHEK | NSLLEHKILE | 
    250:
    MEGKHKEELD | TLKEEKENLQ | GLVTRQTYII | QELEKQLNRA | TTNNSVLQKQ | 
    300:
    QLELMDTVHN | LVNLCTKEGV | LLKGGKREEE | KPFRDCADVY | QAGFNKSGIY | 
    350:
    TIYINNMPEP | KKVFCNMDVN | GGGWTVIQHR | EDGSLDFQRG | WKEYKMGFGN | 
    400:
    PSGEYWLGNE | FIFAITSQRQ | YMLRIELMDW | EGNRAYSQYD | RFHIGNEKQN | 
    450:
    YRLYLKGHTG | TAGKQSSLIL | HGADFSTKDA | DNDNCMCKCA | LMLTGGWWFD | 
    498:
    ACGPSNLNGM | FYTAGQNHGK | LNGIKWHYFK | GPSYSLRSTT | MMIRPLDF
    3D Structure:
    N/A
    Predicted Eptitope:
    Please Sign in.
    EIAab Sequence  Vaild Sequence:
    Please Sign in.
    Related Databases
    UniGene:
    Pfam:
    String:
    MIM:
    SMR:
    KEGG:
    Uniprot:
     
    FOR
    ELISA Kit for Human ANG-1
    Cat.:
    E0008h
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    Range:
    Please sign in first.
    ELISA Kit for Human ANG-1
    Cat.:
    E0008m
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    Range:
    Please sign in first.
    ELISA Kit for Human ANG-1
    Cat.:
    E0008r
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    Range:
    Please sign in first.
    ELISA Kit for Human ANG-1
    Cat.:
    E0008p
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    Range:
    Please sign in first.
    ELISA Kit for Human ANG-1
    Cat.:
    E0008b
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    ELISA Kit for Human ANG-1
    Cat.:
    E0008d
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    CLIA Kit for Human ANG-1
    Cat.:
    U0008d
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    CLIA Kit for Human ANG-1
    Cat.:
    U0008r
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    Range:
    Please sign in first.
    CLIA Kit for Human ANG-1
    Cat.:
    U0008p
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    Range:
    Please sign in first.
    CLIA Kit for Human ANG-1
    Cat.:
    U0008m
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    Range:
    Please sign in first.
    CLIA Kit for Human ANG-1
    Cat.:
    U0008h
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    Range:
    Please sign in first.
    CLIA Kit for Human ANG-1
    Cat.:
    U0008b
    Price:
    Please sign in first.
    MSDS:
    Please sign in first.
    Packing:
    96T
    Polyclonal Antibody for Human ANG-1
    Cat.:
    P0008Rb-h
    Price:
    Please sign in first.
    Packing:
    40ug/0.2ml
    Polyclonal Antibody for Human ANG-1
    Polyclonal Antibody for Human ANG-1
    Polyclonal Antibody for Human ANG-1
    Cat.:
    P0008Rb-m
    Price:
    Please sign in first.
    Packing:
    40ug/0.2ml
    Polyclonal Antibody for Human ANG-1
    Cat.:
    P0008Rb-r
    Price:
    Please sign in first.
    Packing:
    40ug/0.2ml
    Polyclonal Antibody for Human ANG-1
    Monoclonal Antibody for Human ANG-1
    Monoclonal Antibody for Human ANG-1
    Monoclonal Antibody for Human ANG-1
    Monoclonal Antibody for Human ANG-1
    Monoclonal Antibody for Human ANG-1
    Monoclonal Antibody for Human ANG-1
    Protein for Human ANG-1
    Protein for Human ANG-1
    Protein for Human ANG-1
    Protein for Human ANG-1
    Protein for Human ANG-1
    Protein for Human ANG-1

    R&D Technical Data
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    Precision
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    Recovery
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    Linearity
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    For more information, please refer to the manual,Or contact our technical support: tech@eiaab.com.
    Citations
    [1].
    Yesildal F, Koc E, Tas A, et al.
    References
    1. 1.
      "Isolation of angiopoietin-1, a ligand for the TIE2 receptor, by secretion-trap expression cloning."
      Davis S. , Aldrich T.H. , Jones P.F. , Acheson A. , Compton D.L. , Jain V. , Ryan T.E. , Bruno J. , Radziejewski C. , Maisonpierre P.C. , Yancopoulos G.D.
      Cell87:1161-1169(1996) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 2)
      tissue: Fetal lung.
    2. 2.
      "Human angiopoietin-1 mRNA variant form."
      Nakatsukasa M. , Komai K. , Shiozawa S.
      Submitted (2002-04) to the EMBL/GenBank/DDBJ databases
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 2)
    3. 3.
      "Human angiopoietin-1 mRNA variant forms."
      Shan Z.X. , Yu X.Y. , Lin Q.Y. , Fu Y.H. , Tan H.H. , Zheng M. , Lin S.G.
      Submitted (2002-06) to the EMBL/GenBank/DDBJ databases
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 2)
    4. 4.
      "Prediction of the coding sequences of unidentified human genes. I. The coding sequences of 40 new genes (KIAA0001-KIAA0040) deduced by analysis of randomly sampled cDNA clones from human immature myeloid cell line KG-1."
      Nomura N. , Miyajima N. , Sazuka T. , Tanaka A. , Kawarabayasi Y. , Sato S. , Nagase T. , Seki N. , Ishikawa K. , Tabata S.
      DNA Res.1:27-35(1994) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1)
      tissue: Bone marrow.
    5. 5.
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1)
      tissue: Small intestine.
    6. 7.
      "The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)."
      The MGC Project Team
      Genome Res.14:2121-2127(2004) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1)
    7. 8.
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]
    8. 9.
      "Construction of expression-ready cDNA clones for KIAA genes: manual curation of 330 KIAA cDNA clones."
      Nakajima D. , Okazaki N. , Yamakawa H. , Kikuno R. , Ohara O. , Nagase T.
      DNA Res.9:99-106(2002) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: SEQUENCE REVISION
    9. 10.
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: FUNCTION;INTERACTION WITH TEK
    10. 11.
      "Angiopoietin-1 and angiopoietin-2 share the same binding domains in the Tie-2 receptor involving the first Ig-like loop and the epidermal growth factor-like repeats."
      Fiedler U. , Krissl T. , Koidl S. , Weiss C. , Koblizek T. , Deutsch U. , Martiny-Baron G. , Marme D. , Augustin H.G.
      J. Biol. Chem.278:1721-1727(2003) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: INTERACTION WITH TEK
    11. 12.
      "Biological characterization of angiopoietin-3 and angiopoietin-4."
      Lee H.J. , Cho C.H. , Hwang S.J. , Choi H.H. , Kim K.T. , Ahn S.Y. , Kim J.H. , Oh J.L. , Lee G.M. , Koh G.Y.
      FASEB J.18:1200-1208(2004) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: FUNCTION IN REGULATION OF ANGIOGENESIS; CELL SURVIVAL; CELL MIGRATION AND ACTIVATION OF AKT1;INTERACTION WITH TEK/TIE2
    12. 13.
      "Differential function of Tie2 at cell-cell contacts and cell-substratum contacts regulated by angiopoietin-1."
      Fukuhara S. , Sako K. , Minami T. , Noda K. , Kim H.Z. , Kodama T. , Shibuya M. , Takakura N. , Koh G.Y. , Mochizuki N.
      Nat. Cell Biol.10:513-526(2008) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: FUNCTION IN REGULATION OF ENDOTHELIAL CELL MIGRATION AND CELL SPREADING
    13. 14.
      "Angiopoietins assemble distinct Tie2 signalling complexes in endothelial cell-cell and cell-matrix contacts."
      Saharinen P. , Eklund L. , Miettinen J. , Wirkkala R. , Anisimov A. , Winderlich M. , Nottebaum A. , Vestweber D. , Deutsch U. , Koh G.Y. , Olsen B.R. , Alitalo K.
      Nat. Cell Biol.10:527-537(2008) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: FUNCTION IN REGULATION OF ENDOTHELIAL CELL MIGRATION
    14. 15.
      "Control of vascular morphogenesis and homeostasis through the angiopoietin-Tie system."
      Augustin H.G. , Koh G.Y. , Thurston G. , Alitalo K.
      Nat. Rev. Mol. Cell Biol.10:165-177(2009) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: REVIEW
    15. 16.
      "Angiopoietin-1/Tie2 receptor signaling in vascular quiescence and angiogenesis."
      Fukuhara S. , Sako K. , Noda K. , Zhang J. , Minami M. , Mochizuki N.
      Histol. Histopathol.25:387-396(2010) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: REVIEW
    16. 17.
      "Targeting the ANGPT-TIE2 pathway in malignancy."
      Huang H. , Bhat A. , Woodnutt G. , Lappe R.
      Nat. Rev. Cancer10:575-585(2010) [PubMed] [Europe PMC] [Abstract]
      [15/1/25 17:38] Upload to ab completed in less than a minute: 1 file transferred (13.4 Kb/s) Cited for: REVIEW
    Product Feedback Wall
    Hot Genes
    Atf2 ASPRO ACE ALCAM C19orf80 Trap1a Gdf5
    Top Searches
    Ubiquitin-protein ligase metalloproteinase Ubiquitin ELISA Tumor necrosis Alpha Asprosin TRAP1A
    Why choose EIAAB
    Our products have been quoted by many publications in famous journals such as Cell; Cell Metabolism; Hepatology; Biomaterials.more
    Further Information
    About us Protein center Bank account Distributors Terms & Conditions Career eiaab.com.cn

    Copyright & copy www.eiaab.com2006-2016 All Rights Reserved    EIAab         Email:eiaab@eiaab.com

    鄂ICP备10015095号-1

    鄂公网安备 42018502005535号

    Twitter