PDCD1 and neoplasm: Interestingly, tumor-specific infiltrating T helper cells showed a drastic upregulation of PD-1, TIM-3, and CTLA4 expression; whereas tumor-specific infiltrating cytotoxic T cells exhibited a significant increase of PD-1, TIM-3, LAG-3, and CTLA4 expression, compared with their counterparts in tumor-free liver tissues and in blood [46].