To elucidate the contribution of CCR1+ CXCR2+ myeloid cells in CRC progression, we further performed BM transfer experiments using 4 groups: wild-type BM, Ccr1−/− BM, Cxcr2−/− BM and Ccr1−/−Cxcr2−/− BM (Fig. 6a). Here, CCR1 is linked to colorectal carcinoma.