MAP2K2, also known as MEK2, belongs to the STE grouping of kinases. Both MEK2 and the related MEK1 are dualspecificity kinases, phosphorylating and activating the mitogen-activated protein kinases ERK1 and ERK2 at T and Y positions within the phosphoacceptor sequence T-E-Y. MAP2K2 is activated by a wide variety of growth factors and cytokines and also by membrane depolarization and calcium influx.