CD274 and colorectal carcinoma: In CRC, CAFs, owing to their expression of PD-L1/2 molecules, suppress the proliferative response of activated CD4+T cells by impeding IL-2 production or elicit immunosuppression through the secretion of CXCL5, which subsequently activates the PI3K/AKT pathway to induce PD-L1 expression in cancer cells [72, 73].