PTEN and melanoma: To establish whether MHC class II up-regulation in melanocytes is specific to activated BRAFV600E or also triggered by other perturbations of melanoma oncogenic and tumor suppressor pathways, melanocytes were transduced with activated oncogenes, HRASG12V and NRASQ61K, activated MEK1Q56P (Emery et al., 2009), and activated myrAKT, as well as two short hairpin RNAs to stably knock down PTEN (Figure 2f).