Mitogen-activated protein kinase 15, also known as MAPK15, ERK7, or ERK8, is an enzyme that in humans is encoded by the MAPK15 gene. The protein encoded by this gene is a member of the MAP (mitogen-activated protein) kinase family. MAP kinases are also known as extracellular signal-regulated kinases (ERKs), and are involved in signaling cascades that regulate a number of cellular processes, including proliferation, differentiation, and transcriptional regulation. In vertebrate models, ERK8 is not constitutively active, and exhibits relatively low basal kinase activity. It contains two SH3 (SRC homology 3) binding motifs in its C-terminal region, and is likely activated by an SRC-dependent signaling pathway. SRC is a non-receptor tyrosine kinase (and proto-oncogene) that has been implicated in cancer growth and progression in humans when it is overexpressed. The exact function of MAPK15 is unknown, though a number of studies have implicated the enzyme in various cellular pathways.