ECTO-NOX family comprise NAD(P)H oxidases of plants and animals exhibiting both oxidative and protein disulfide isomerase-like activities. it is named because of their cell surface location.

The two biochemical activities, hydroquinone [NAD(P)H] oxidation and protein disulfide–thiol interchange alternate, a property unprecedented in the biochemical literature.

At least two forms of ECTO-NOX activities have been distinguished on the basis of response to ormones, growth factors, capsaicin (8-methyl-Nvanillyl-6-noneamide), and certain other quinone-site inhibitors or potential quinone-site inhibitors with anticancer activity.

A tumor-associated ECTO-NOX (tNOX) is cancer-specific and drug-responsive. The constitutive ECTO-NOX (CNOX) is ubiquitous and refractory to drugs. The physiological substrate for the oxidative activity appears to be hydroquinones of the plasma membrane such as reduced coenzyme Q10. ECTO-NOX proteins are growth-related and drive cell enlargement.

CNOX proteins are widely distributed and exhibit activity oscillations with period lengths of 24 min. tNOX proteins are cancer specific and exhibit oscillations with period lengths of about 22 min, shorter than those of CNOX.

tNOX is found in the sera of cancer patients with a wide variety of cancers including breast, prostate, lung and ovarian cancers, leukemias, and lymphomas. But not found in the serum of healthy volunteers or patients with disorders other than cancer. 

Wuhan EIAab Science Co., devotes to the research and development of lifescience. The company offers the ELISA Kit (Cat No.E0381h) for quantitative detection of Human CNOX and ELISA kit (Cat No. 15186h) for Human tNOX.