GATM and neoplasm: The results of both experimental and clinical studies have indicated that AGAT activity is an important determinant of tumour sensitivity to several types of DNA-damaging agents, such as methylating and chloroethylating agents, which target the O6 position of guanine (Dumenco et al, 1989; Schold et al, 1989; Pegg, 1990; Esteller et al, 2000).