Based on the data that both host-derived CCL5 and tumor cell-derived CCL5 play important role on tumor progression in CRC, we chose KO + CT26shCCL5 (CCL5−/−) mice and the control group WT + CT26shNTC (CCL5+/+) to explore the role of CCL5 in CRC in the following studies. The gene discussed is CCL5; the disease is colorectal carcinoma.