While the conditional BRAFV600E/PTEN knockout mouse model is well-known for its robust metastatic melanoma phenotype [86], and PI3K/AKT signaling indeed underlies the phenotype [87], these lesions would seem unlikely to provide strong pro-metastatic effects in the HGF/SF mouse where signaling via the RAS/RAF/MAPK and PI3K pathways is already constitutively active [88]. This evidence concerns the gene AKT1 and melanoma.