CD274 and colorectal carcinoma: In CRC cell lines, observed PD-L1 expression is scarce and below the detection level of IHC techniques, whereas it is predominantly seen in the surround ding myeloid cells; this presentation is unusual in comparison with other immunogenic tumors such as renal or lung cancer, which may explain why PD-L1 is not a trustworthy biomarker for CRC [17].