NRAS and non-small cell lung carcinoma: Additionally, in previous studies we reported the incidence of KRAS (23 %), EGFR (6 %), DDR2 (2 %), PIK3CA (2 %), NRAS (1.5 %), HER2 (<1 %), AKT1 (<1 %) and PTEN (<1 %) genes mutations in CNS metastases of NSCLC.None of these mutations coexisted with a 184 mutation in MEK1 gene that was detected in this analysis.