IFNG and neoplasm: In addition to IFN-γ, several other inflammatory cytokines also enhance PD-L1 expression on cancer cells or tumor-associated stromal cells, such as IFN-α/β [66], Toll-like receptors3/4 [63, 73], TNF-α [103], TGF-β [104], and IL-4/6/10/17/27 [64, 65, 71, 72, 105].