Dual specificity mitogen-activated protein kinase kinase 2, also known as MAP kinase kinase 2, MAPKK2, ERK activator kinase 2, MAPK / ERK kinase 2, MEK2 and MAP2K2, is a member of the protein kinase superfamily, STE Ser/Thr protein kinase family and MAP kinase kinase subfamily. MAP2K2 / MEK2 contains oneprotein kinase domain. MEK1 and MEK2 (also known as MAP2K1 and MAP2K2, respectively) are evolutionarily conserved, dual-specificity kinases that mediate Erk1 and Erk2 activation during adhesion and growth factor signaling. MAP2K1 / MEK1 is a crucial modulator of Mek and Erk signaling and have potential implications for the role of MEK1 and MEK2 in tumorigenesis. MAP2K2 / MEK2 catalyzes the concomitant phosphorylation of a threonine and a tyrosine residue in a Thr-Glu-Tyr sequence located in MAP kinases. It also activates the ERK1 and ERK2 MAP kinases. Defects in MAP2K2 are a cause of cardiofaciocutaneous syndrome (CFC syndrome) which is characterized by a distinctive facial appearance, heart defects and mental retardation. Heart defects include pulmonic stenosis, atrial septal defects and hypertrophic cardiomyopathy.