CD274 and cancer: In that sense, it is known that PD-L1 is involved in two types of immune resistance mechanisms that can co-exist: i) intrinsic, referred to PD-L1 expression induced by certain signalling pathways, AKT and STAT3, in cancer cells, and ii) adaptive, referred to the auto-induction of this ligand by the presence of some cytokines such as IFN-γ [4].