RET and medullary thyroid gland carcinoma: In this preclinical study, we evaluated the potential antitumor activity of new TKIs in MTC, focusing on molecules targeting FGFR-1/VEGFR (SU5402, inhibitor of FGFR-1 and VEGFR-2; sulfatinib, inhibitor of FGFR-1 and VEGFR-1/2/3) and RET (SPP86, a RET-specific inhibitor).