In a previous study using MEK (a downstream effector of KRAS and BRAF) inhibitors, it was demonstrated that BRAF mutant cell lines responded differently than those bearing mutant KRAS, raising the possibility that KRAS and BRAF mutant cancer cells might be differentially dependent on signalling mechanisms that involve MEK, a scenario also supported by the mutual exclusivity of these two mutations [157]. The gene discussed is MAP2K7; the disease is cancer.