ERK1 and ERK2 (E, Xenopus/Amphibian,tracellular signal-regulated kinase 1 and 2) are members of the MAP kinase signal transduction pathway. The activation of signal transduction pathways by growth factors, hormones and neurotransmitters is mediated through two closely related MAP kinases,Porcine44 and p42 encoded by ERK1 and ERK2 respectively. Both kinases are regulated by dual specific phosphorylation on tyrosine and threonine in response to insulin and NGF. ERK1 and ERK2 are involved in both the initiation and regulation of meiosis,Mouse,itosis, and postmitotic functions in differentiated cells by phosphorylating a number of transcription factors such as ELK1.