FLT4 and neoplasm: Regorafenib is a different oral MKI that potently blocks multiple protein kinases involved in tumor angiogenesis (VEGFRs 1–3, TIE2), oncogenesis (KIT, RET, RAF-1, BRAF), metastasis (VEGFR3, PDGFR, fibroblast growth factor receptor), and tumor immunity (CSF1R) [10, 11].