APOBEC3A and squamous cell carcinoma: Squamous cell carcinomas (notably of the head and neck (HNSC), cervix (CESC-SQ), oesophagus (ESCA-SQ), lung (LUSC) and bladder (BLCA) were among the cancers with highest APOBEC3A expression (Fig. EV2A), and these also displayed the highest GRHL3 expression (Fig. EV2B) and activity scores (as inferred from the expression of genes in the GRHL3 regulon identified in our earlier SCENIC analysis, Fig. EV2C).