WEE1 and neoplasm: Regorafenib is an oral multikinase inhibitor [19] that blocks the activity of multiple protein kinases involved in angiogenesis (vascular endothelial growth factor receptor (VEGFR)-1, -2, -3 and tyrosine kinase with immunoglobulin and epidermal growth factor homology domain 2 (TIE-2, a crucial regulator of angiogenesis)) [20], oncogenesis (c-kit, Raf-1, c-Ret and V600E-mutated B-Raf), metastasis and the tumor microenvironment (platelet-derived growth factor receptor; and fibroblast growth factor receptor) [19].