PRF1 and hepatocellular carcinoma: In hepatocellular carcinoma (HCC), tumor tissue localized MAIT cells also exhibited exhausted phenotype with upregulation of inhibitory immune molecules (PD-1, CTLA-4, and TIM-3) and secreted lower quantities of effector molecules (e.g., IFN-g, granzyme B, and perforin) (87).