GZMB and neoplasm: It is also important to note that, unlike other novel cytotoxic enzymes of human origin (e.g., granzyme B and angiogenin) that are mostly limited as a result of upregulation of their endogenous inhibitors by target cells, DAPk1 and DAPk2 with its autoregulatory CaM domain removed theoretically are able to bypass tumor drug escape or resistance mechanisms.