CCR2 and renal fibrosis: Another article clarified that CCR2 participates in the recruitment of bone marrow-derived fibroblasts into the kidney during the development of renal fibrosis, thus we speculated CCR2 may promote tumor development by recruiting some bone marrow-derived fibroblasts into the tumor sites and then become cancer associated fibroblasts(CAF) in the tumor microenvironment [40].