CD274 and neoplasm: Programmed cell death ligand-1 (PD-L1, ligand for PD-1; also known as B7-H1 or CD274) on tumor cells is upregulated by constitutive oncogenic signaling (innate resistance) or by inflammatory signals in the tumor microenvironment (adaptive resistance), such as interferon-γ (INF-γ) produced by some activated T cells and natural killer cells [9].