FGFR1 and medullary thyroid gland carcinoma: In light of these arguments, the aim of this preclinical study was to investigate the efficacy of novel TKIs in MTC: SU5402, a selective inhibitor for fibroblast growth factor receptor type 1 (FGFR-1) and VEGFR-2 [19,20,21]; sulfatinib, targeting FGFR-1 and VEGFR-1/2/3; and SPP86, a RET-specific inhibitor.