MKI67 and head and neck squamous cell carcinoma: Given the strong evidence from both single cell and bulk RNA-seq data that implicates GRHL3 in APOBEC3A regulation in HNSCC, we next analysed RNA-seq data from the 34 HNSCC cell lines in the Cancer Cell Line Encyclopaedia (CCLE) (Ghandi et al, 2019), observing correlations between APOBEC3A, GRHL3 and differentiation-related genes, and inverse correlations between APOBEC3A and proliferation markers, MKI67, MCM7 and TOP2A (Fig. EV3A).