In addition, some downstream pathways are involved (the RAS–MAPK and the PI3K–AKT–mTOR pathways) in cell differentiation and survival via the RAS family.79 The most mutated RAS family gene in lung cancer is KRAS.28 KRAS mutations occur in 20–40% of lung adenocarcinomas, which make up ~20% of cases in Western countries and ~10% of cases in Asian countries.80 Some studies have showed that KRAS mutations may be factors in EGFR-TKIs resistance in targeted therapies in NSCLC.29 Therefore, various agents attempt to target the RAS pathway in NSCLC to overcome drug resistance. Here, KRAS is linked to lung cancer.