For example, trametinib acts more potently on MEK when it is complexed with RAF rather than on free MEK (Gonzalez-Del Pino et al., 2021), whereas other MEK inhibitors induce the formation of these MEK/RAF complexes in KRAS-mutant lung cancer cell lines, which prevents durable inhibition of ERK (Lito et al., 2014). This evidence concerns the gene MAP2K7 and lung cancer.