Analysis of lungs from both the BRAFV600E;Trp53-null model and the BRAFV600E;Pten-null model revealed a low number of lung nodules in Rac1WT/WT mice, which were in part benign primary bronchoalveolar tumors and in part genuine melanoma metastases (Figures S6J–S6N). This evidence concerns the gene PTEN and melanoma.