CD34 and acute lymphoblastic leukemia: Likewise, we found that xenotranplants of shRNA-mediated knockdown of VAV330 in leukemic progenitors from a Ph+ B-ALL patient (CD34+/CD19+; Fig. 1K) reduces by ~60–75% the level of human leukemic progenitor chimera (hCD45+ hCD34+ hCD19+ EGFP+) present in the bone marrow of the transplanted immunodeficient recipients (Fig. 1L and Supplementary Fig. 1F).