TDG and melanoma: However, the fact that untransformed melanocytes are minimally affected by TDG knockdown and only show reduced proliferation starting at 80 h (whereas melanoma cells have marked reduction in cell index starting at 55 h, Fig. 7b–d), and that conditional knockout of TDG in adult mice is well tolerated (Fig. 7f), rules out significant toxicity in normal cells/tissues due to specific TDG inactivation and indicates that it should be possible to achieve an effective therapeutic window.