MAP kinase kinase kinase

MAP kinase kinase kinase (or MAP3K or MEKK) is a serine/threonine-specific protein kinase which acts upon MAP kinase kinase.

In humans there are at least 19 genes:

Perhaps the best characterized MAP3K are the members of the oncogenic RAF family (RAF1, BRAF, ARAF), which are effectors of mitogenic ras signaling and which activate the ERK1/2 (MAPK3/MAPK1) pathway, through activation of MEK1(MAP2K1) and MEK2(MAP2K2).