The PI3K (Phosphatidylinositol 3-kinase)/AKT/mTOR (Mammalian Target of Rapamycin) signaling pathway, linked to enhanced proliferation and migration of SCLC cells, is another frequently altered pathway, with activating mutations found in PIK3CA (Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha), AKT, and PTEN (Phosphatase and Tensin Homolog) genes [16]. This evidence concerns the gene MTOR and small cell lung carcinoma.