The reduction in SBS2 and SBS13a/b was accompanied by a loss of the enrichment of mutations at YTCA sequences, demonstrating that previous observations of APOBEC3A sequence preferences in yeast23 can be extended to endogenous APOBEC3A activity in human cancer cells (Fig. 3i,j and Extended Data Fig. 6e,h). Here, APOBEC3A is linked to cancer.