The ensemble of molecular studies has provided the recognition of the main somatic genetic lesions occurring in the two main tumor subtypes: thus, EGFR and KRAS mutations and ALK-EML4 fusions mainly occur in adenocarcinomas, while DDR2, FGFR2 and NFE212 mainly occur in squamous cell carcinomas. The gene discussed is KRAS; the disease is adenocarcinoma.