MAPK3 and breast cancer: ERα regulates cell proliferation, differentiation and survival in BC, its activity being regulated by phosphorylation through various kinase signaling pathways [77], including c-Src kinase and the extracellular-signal-regulated kinase 1/2 (ERK1/2) signaling pathways [77], mitogen-activated protein kinase RAS-RAF (RAS-RAF-MAPK) cascade, p38 MAPK pathway, cyclin-dependent kinases CDK2 and CDK7, protein kinase C (PCK), pp90 RSK1, protein kinase B (AKT/PKB), IKKα kinase, and protein kinase A (PKA) [78].