Using data obtained from human melanoma samples, which demonstrated increased levels of phosphorylated AKT (P-AKT) and decreased levels of phosphatase and TENsin homolog deleted on chromosome 10 (PTEN) in brain metastases,2,3,4 we generated a mouse model of melanoma with hyperactivation of AKT1 signaling that develops lung and brain metastases similar to the human disease. The gene discussed is PTEN; the disease is melanoma.