Since our Braf-Pten mouse melanoma model retained one functional allele of Pten, we hypothesized that Brn2 loss would induce less expression from the WT Pten allele, leading to the increased PI3K-AKT signaling observed (Supplementary Fig. 5D) and consequent melanoma initiation and proliferation. This evidence concerns the gene POU3F2 and melanoma.