Its constitutive activation is caused by mutations or altered stimulation of pathway components (mainly RAS, RAF, MEK) and leads to the hyperactivation of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase 1 and 2 (ERK1/2), which promote tumor cell growth (Samatar and Poulikakos, 2014). Here, MAPK3 is linked to neoplasm.