E4F1 and melanoma: To further establish the binding of E4F1 or IRF2 to rs3769823, we performed chromatin immunoprecipitation (ChIP) for E4F1 or IRF2 followed by quantitative PCR, noting an enrichment of binding at rs3769823 in melanoma cell lines with homozygous for rs3769823-A as well as primary melanocytes heterozygous for this variant (Figures 4E and S25B).