MEK1, phosphorylated (Ser221) (MAPK/ERK Kinase 1, MEK 1, Dual Specificity Mitogen-Activated Protein Kinase Kinase 1, MAP Kinase Kinase 1, MAP2K1, MAPKK 1, MKK1, PRKMK1, ERK Activator Kinase 1)

MAP kinase kinase (Mek1), also known as mitogen activated protein kinase kinase, MAP kinase kinase, ERK kinase 1 or microtubule-associated protein 2 kinase, is a 43kD dual-specificity protein kinase that phosphorylates threonine and tyrosine residues on MAP kinases such as Erk 1 and 2. Phosphorylation by Mek1 increases Erksí ability to phosphorylate micrtubule-associated proteins and myelin basic proteins. Mek1 is involved in diverse arrays of cellular processes such as stress-activated response, apoptosis, cytokine-induced cell proliferation, and DNA recombination during meiosis. Mek1 is activated...