CD274 and neoplasm: PD-L1 expression can be induced by inflammatory cytokines, such as interferon (IFN)-γ [10] secreted by infiltrating lymphocytes or induced by tumor-cell intrinsic signaling, including nuclear factor (NF)-κB, mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K), mammalian target of rapamycin (mTOR) and Janus kinase/signal transducers and activators of transcription (JAK/STAT) [11].