UNG and cancer: These data indicate that UNG activity is required for the generation of C>G and C>A mutations following cytosine deamination in human cells, consistent with previous reports from engineered model systems (Chan et al., 2012, Di Noia and Neuberger, 2007, Taylor et al., 2013), and thus add further weight of evidence to the hypothesis that APOBEC deaminases are the sources of SBS2 and SBS13 in human cancer.