NRAS^Q61K sensitizes for apoptosis by MEK inhibitors. (A-C) All 4 CTCL cell lines were incubated with indicated concentrations of MEK inhibitors U0126 (A), AZD6244 (B), and PD0325901 (C) for 48 hours (left) and 72 hours (right). Then, apoptosis was determined, and specific apoptosis was calculated as described in “Cell death assays.” Data are representative at least 3 independent experiments.