KRAS and squamous cell carcinoma: KRAS is the most commonly mutated oncogene in non-small cell lung cancer (NSCLC), occurring mainly in lung adenocarcinomas (30%) and less frequently in squamous cell carcinoma (5%) (2, 3) Treatments directed toward KRAS mutations are not available because of limited efficacy resulting from failure to inhibit the protein directly, or inhibit its downstream effectors (4).