Expression of

ABCG2 in human hematopoiesis. (A-E) FACS diagrams illustrate the sorting gates used to isolate putative stem cells and committed progenitors. (A) SP cells, (B) CD34⁺/CD38⁻ and CD34⁺/CD38⁺ cells, (C) CD34⁺/ KDR⁺, (D) CD34⁺/CD10⁺ cells, and (E) CD34⁺/CD33⁺ cells. (F) RT-PCR forABCG2 expression in the representative sorted cell populations shown above. Both ABCG2 and GAPDHwere amplified for 36 cycles. (G) Semiquantitative analysis ofABCG2 expression in sorted cell populations. Each bar represents an independent sort. All values are taken from 36 cycle amplifications and are normalized to GAPDH values from the same sample. All values below 50 were in the linear range of the PCR, as determined by an ABCG2 cDNA standard curve. Values above 50 are probably slight underestimates. The asterisk indicates normalized ABCG2 values below 1 on this arbitrary scale. The double asterisks indicate duplicate samples with values below 1.