DLL4 and neoplasm: The tested anti-angiogenic drugs span a wide range with respect to both mechanism of action and state of clinical utilization: Axitinib (AXI), a potent VEGF-R2 inhibitor approved for the treatment of renal cell carcinoma37, LDC 1267, also a tyrosine kinase inhibitor (TKI), targeting the TAM-receptor family (Tyro3, Axl, Mer)38, and Deshydroxy (DesOH) LY-411575 a γ-secretase inhibitor that significantly affects tumor angiogenesis and pathological sprouting via the Dll4/Notch signaling pathway39.