CD274 and neoplasm: Korehisa et al. reported that in colon cancer patients with high microsatellite instability PD-L1 is mainly expressed by aggressive front-end tumor cells and CD68/CD163-positive M2 macrophages, and PD-L1 expression is associated with features, such as poor tumor differentiation, lymphatics, etc. Gordon and collaborators found that PD-1 expression by TAMs increased as the disease progressed.