JAG1 and B-cell chronic lymphocytic leukemia: In contexts other than CLL, Jag1 is processed by an ADAM-like activity liberating a soluble extracellular fragment (sJag1-EC) which regulates Notch signaling in neighboring cells11,44, and a membrane-associated fragment (Jag1-TM) which is cleaved by γ-secretase generating a transcriptionally active Jag1 domain (Jag1-IC)6,10.