MAPK1 and breast cancer: After binding to its receptor CXCR2, CXCL1 activates many pathways implicated in breast cancer including phosphatidylinositol-4,5-bisphosphate 3-kinase-γ (PI3Kγ)/Akt, MAP kinases such as ERK1/ERK2 or phospholipase-β (PLCβ) signaling pathways.