Kemmerich K et al. (2012) reported that mice carrying a loss of SMUG1 and UNG in combination with loss of mismatch repair (Msh2 −/−) had shortened life spans and increased tumor formation, which implies a role for SMUG1 in protecting cells from the genomic instability that induces cancer, perhaps through direct removal of hmdU moieties [29]. Here, UNG is linked to neoplasm.