IL2 and B-cell chronic lymphocytic leukemia: VLA-4 plays a key role in the retention of hematopoietic progenitors in BM stroma, which is required for normal early B cell development.[4] The second prognostic indicator, CD38, is a promiscuous glycoprotein that functions as an ectoenzyme, a surface receptor, and an adhesion molecule.[5] In CLL, CD38 ligation in the presence of IL-2 induces the survival and proliferation of the tumor cells.[6], [7] Furthermore, CLL cells expressing CD38 are thought to have enhanced migratory capacity.[8], [9]