KIT and neoplasm: Overexpression of several receptors such as the VEGFR (vascular endothelial growth factor receptor) on endothelial cells, the EGFR (epidermal growth factor receptor, the c-KIT, the PDGFR (platelet derived growth factor receptor) and the FGFR (fibroblast growth factor receptor), on tumor cells has prompted the scientific community to evaluate the efficacy and safety of new molecules targeting signaling pathways controlled by these proteins in metastatic SCLC (bevacizumab, sunitinib, sorafenib, pazopanib, Imatinib, cetuximab, erlotinib, Gefitinib, lapatinib, everolimus, bortezomib) (Figure 3).