Indeed, GrB is produced and secreted by immune cells, like T and B cell subpopulations, monocyte/macrophages, mast cells, and basophils (8–13), by non-immune cells, like vascular smooth muscle cells (V-SMCs), pneumocytes, keratinocytes, and chondrocytes (12, 14–16), as well as by tumor cells, like leukemia cells and breast, urothelial, prostate, pancreatic and colorectal cancer cells (17–21) (Table 1). This evidence concerns the gene GZMB and neoplasm.