Mitogen-activated dual threonine/tyrosine kinases (MAPK/ERK kinase, MAPKK, MAP2K) that phosphorylate and activate MAP kinases (MAP kinase kinases). MEK1 (393 aa) shares 80% sequence identity with MEK2 (400 aa). MEK3 (MKK3; MAP2K3), MEK4 (MKK4; MAP2K4), and MEK6 (MKK6) activate JNK and p38 MAP kinases with variable selectivity, but not ERK. If MEKs are constitutively activated (e.g. by raf) the result is cell transformation. Mutation in MEK1 leads to cardiofaciocutaneous syndrome.
Subjects: Medicine and Health.