Limited preclinical studies reported that (S)-crizotinib, and not the (R)-enantimer, induces strong anti-proliferative effects of a panel of human cancer cell lines and inhibits xenograph tumor growth of SW480 cells10, which is believed to be attributed to inhibition of MTH1 (MutT Homolog 1), a nucleotide pool sanitizing enzyme10,11. The gene discussed is NUDT1; the disease is cancer.