CXCL1 and cancer: Aberrant expression/signaling of CXCR2 and of its multiple ligands, including several CXC chemokines GRO-α, plays crucial role in carcinogenesis by promoting cancer cell proliferation, migration, and invasion, as well as angiogenesis and by contributing to chemo- and radioresistance in many cancers [28,29,30,31,32,33,34,35].