CXCR2 and nonpapillary renal cell carcinoma: Mechanistically, CXCL7 enhances the activity of the PI3K/AKT/mTOR and ERK cell proliferation signaling pathways by binding to the CXCR1 and CXCR2 ccRCC cell membrane receptors and exerting a proliferative effect on tumor cells (Figure 1) (Grépin et al., 2014).