GZMB and neoplasm: So far, various endogenous pro-apoptotic molecules such as granzyme B (GrB) [88], truncated Bid (tBid) [94], caspase-3 [93], caspase-6 [92, 146] and apoptosis-inducing factor (AIF) [147] have been utilized to induce apoptosis in tumor cells (Table 2).