CD34 and acute leukemia: Our miR microarray expression analyses [32] (GEO Series accession number GSE51908) revealed undetectable endogenous levels of mature miR-509-5p and miR-509-3p in NALM6 and other acute leukemia cell lines (Figure 1D, 1E), as well as in primary leukemia cases and CD34+ hematopoietic stem-progenitor cells (HSPCs) and blood cell types from normal human donors (Figure 1D, 1E).