CD274 and colorectal carcinoma: The increased expression of PD-L1 has been observed in the specimens and cell lines of CRC patients with KRAS mutation, which may increase the stability of PD-L1 mRNA by regulating the AU-rich element-binding protein tristetraprolin (TTP), and the combined blocking of anti-EGFR and PD-1/PD-L1 significantly inhibits tumor growth [232,233].