MAPK3 and breast carcinoma: As a major receptor of NMU which was already considered as a tumor growth and/or progression marker in endometrial, renal, and breast cancers, NMUR1 could interact with NMU leading to autocrine tumor-promoting pathway activation, including intracellular Caflux, the phosphorylation of ERK1/2 kinases and hypoxia-inducible factors activation.9