PTEN and melanoma: To further confirm the importance of PERK in resistance to BRAF inhibition in BRAFV600E mutant melanoma with impaired PTEN, we introduced a wild-type form and a function lost mutant form of PERK into both parental BRAFV600E-mutant melanoma cells Sk-mel28 and WLH6215 and tested resistance to BRAF inhibition.