CD274 and colorectal cancer: Initially, two panels of tumor cell lines, gastric cancer cells (HGC27, MNK45, SNU216, SGC7901, and MGC803) and colorectal cancer cells (SW480, HT-29, RKO, and HCT116) were screened at the mRNA and protein levels for the detection of their constitutive expression of PD-L1 molecule (Supplementary Figure S2A).