KRAS and lung carcinoma: However, while lung cancer in never smokers with EGFR driver mutations may be sensitive to EGFR tyrosine kinase inhibitor (EGFR TKI) treatment, lung cancers in smokers with KRAS mutations are often resistant to EGFR TKI treatment underscoring that upstream activation of EGFR is not necessary for the Ras activity in these patients [6].