CXCR1 and colorectal carcinoma: In another study, Li et al. [26] observed a differential expression of CXCL8 and its receptors, CXCR1 and CXCR2, in human CRC cells with different metastatic potentials by adding a certain amount of exogenous CXCL8 to their culture medium; in this study, the mRNA and protein expression levels of CXCL8 as well as CXCR1 and CXCR2 were significantly lower in nonmetastatic (Caco2 cells) and low metastatic (KM12C cells) CRC cells than in high metastatic (KM12L4 cells) CRC cells.