Four types of first-in-class small-molecule inhibitors of MTH1 were recently reported—TH287/TH588, (S)-crizotinib, SCH51344, and organometallic complexes—among which TH287/TH588, (S)-crizotinib, and SCH51344 preferentially kill cancer cells or RAS-transformed fibroblast cells8, 9, 11. Here, NUDT1 is linked to cancer.