DLL4 and neoplasm: The expression of Notch ligand (DLL4) in tumor vasculature is high as compared to healthy tissues.55 In TNBC, DLL4 binding to the Notch receptors promotes the transcription activation of genes regulating tumor angiogenesis and growth.55,56 DLL4 mediated activation of Notch signaling, therefore, improves vascular function and promotes tumor growth.57 Jia et al demonstrated that a humanized anti-DLL4 mAb inhibits breast tumor growth in an MDA-MB-231 xenograft model in mice.