MTOR and small cell lung carcinoma: SCF/c-Kit signaling induces activation of various signaling mediators, including PI3K/Akt/mammalian target of rapamycin (mTOR) pathway and the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK) pathway in SCLC and was inhibited by imatinib [21,30].