DLL4 and breast cancer: Illustrating this, a mAb targeting anti-EGF-like repeats of Notch1 (602.101), sensitive to Ca2+-induced conformational changes of the receptor, prevented the binding of Jagged1, DLL1, and DLL4 and had selective activity against breast cancer CSC, enhancing apoptosis and increasing chemo- and radio-sensitivity of resistant cells [217].