CD274 and neoplasm: However, because PD-L1 expression is regulated by cancer-cell-intrinsic (i.e., PD-L1 gene status and driver oncogenic pathways) and extrinsic (i.e., cytokine milieu) factors [27,28,29], the role of MET in PD-L1 induction might differ according to the tumor type and the tumor microenvironment.