In vitro, TAO (thousand and one amino acid) protein kinase 2 (TAO2) activates MAP/ERK kinases (MEKs) 3, 4, and 6 toward their substrates p38 MAP kinase JNK/SAPK (Chen et al., 1999, Chen and Cobb, 2001). This and more recent work has led to the proposal that the TAO protein kinases play an essential role in signaling from physiological agonists to the stress-responsive p38 MAPKs (Chen et al., 2003). Autophosphorylation of TAO may play a role in the mechanism of TAO activation. The MEK binding domain of TAO is autophosphorylated on both serine and threonine residues and Ser181 is located within this domain.Synonyms: KFC-C, KIAA0881, Kinase from chicken homolog C, MAP3K17, PSK-1, PSK1, Prostate-derived STE20-like kinase 1, Serine/threonine-protein kinase TAO2, Thousand and one amino acid protein 2, UNQ2971/PRO7431