Curcumol inhibits the production of programmed cell death-ligand 1 in hepatocellular carcinoma cells via the hypoxia-inducible factor-1 alpha and the signal transducer and activator of transcription 3 signaling pathways, restoring the tumor-killing capabilities of cytotoxic T lymphocytes [42]. The gene discussed is CD274; the disease is hepatocellular carcinoma.