KRAS and small cell lung carcinoma: Moreover, activation mutations of the oncogenes phosphatidylinositol-4,5-bisphosphate 3-kinase (PIK3CA), epidermal growth factor receptor (EGFR), and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) are often found in SCLC (Tatematsu et al., 2008; Shibata et al., 2009).