PPT1 and neoplasm: A potent antitumor compound, DQ661, has been identified, which specifically targets and inhibits PPT1 in lysosomes, resulting in rapid accumulation of palmitoylated proteins, thereby impairing mTOR and lysosomal catabolism, which in turn significantly inhibiting tumor growth in mouse models of melanoma, colorectal, and pancreatic cancer [135] (Table 1).