CCR5 and colorectal carcinoma: In human CRC, functional CCR5 was highly expressed in tumor-infiltrating Treg cells, and Treg cells expressing high levels of CCR5 are more suppressive; however, the pharmacological inhibition of CCR5 failed to reduce the tumor-infiltrating Treg cells, suggesting that other chemokine receptors are probably involved in the recruitment of Treg cells into the tumor during CRC development [93].