CD274 and colorectal cancer: Therapeutic antibodies blocking the coinhibitory PD-1 pathway by targeting PD-L1 (programmed death 1 ligand 1, also known as B7-H1 or CD274) or its receptor, PD-1, have caused striking regressions in several malignancies in which RAS mutations are frequent driver events, including non-small cell lung cancer (NSCLC) (Herbst et al., 2014, Topalian et al., 2012) and mismatch-repair-deficient colorectal cancer (Le et al., 2015).