SOAT1 and neoplasm: However, the proinflammatory cytokine interferon gamma (IFN‐γ) secreted by tumor‐infiltrating CTLs upregulates negative immune regulators.[24] For example, IFN‐γ induces programmed death ligand 1 (PD‐L1) expression on the tumor cell surface via the Janus kinase‐signal transducer and activator of transcription (JAK‐STAT) signaling pathway.[25, 26, 27] PD‐L1 disables CTLs by binding programmed death receptor 1 on their surface and induces adaptive immune evasion.[28, 29]