MAPK8 and neoplasm: Mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated kinase-1 and 2 (ERK1/2), c-Jun N-terminal kinase (JNK), stress activated protein kinase (SAPK), and p38, are ubiquitous serine/threonine protein kinases, which have been implicated in many cellular processes, including tumor initiation, cell proliferation, differentiation, drug resistance, and apoptosis.