NRAS and melanoma: In order to investigate the effects on cell viability using the MEK/CDK4,6 inhibitor combination, we evaluated the response of 10 NRAS mutant melanoma cell lines to the MEK inhibitor GSK1120212 (trametinib), the CDK4,6 inhibitor PD0332991 (palbociclib) and the combination of both inhibitors in vitro.