Interestingly, upon examination of PERK expression, we found that A375sm PTEN KO-R expressed a higher level of PERK and phosphorylated PERK (Fig. 4a) and was sensitized to PERK inhibition (Fig. 4c), implying that the inactivation of PTEN in melanoma may alter the path to resistance to BRAF inhibition and induce expression of PERK. This evidence concerns the gene BRAF and melanoma.