Knockdown of E4F1 resulted in an increase in CASP8 levels while IRF2 knockdown results in reduction of CASP8 RNA levels in melanoma (Figure 5A and 5B, S27A and S27B), breast cancer (Figure S28A and S28B), and melanocytes (Figure S29A), consistent with respective roles for E4F1 and IRF2 as a potential repressor and activator in cells of melanocytic lineage. This evidence concerns the gene IRF2 and breast carcinoma.