PTEN and melanoma: An additional 4% of BRAF inhibitor resistant melanomas display genetic alterations, including oncogenic AKT1/3 mutations, loss of function PTEN mutations and putative functional mutations in other PI3K regulatory genes (i.e. PIK3CA, PIK3CG, PHLPP1 and PIK3R2) that activate only the PI3K/AKT network5.