CD34 and acute lymphoblastic leukemia: Overcoming this limitation, a novel model of human T-ALL generation has recently been developed, consisting of the reconstitution of NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) immunodeficient mice with human CD34+ umbilical cord blood (CB) hematopoietic progenitors expressing constitutively active NOTCH1 [92].