Coexpression of MPO and β-globin in individual CD34⁺c-kit⁺ AGM cells. (A) Individual cells were subjected to multiplex 2-round RT-PCR using primers specific for CD34, c-kit, MPO, and β-globin. Second-round β-globin and MPO PCR products from CD34⁺c-kit⁺ cells were electrophoresed on an agarose MadgeBio gel, with MPO products on the left side and β-globin products on the right side. The migration direction of the gel is indicated by the large open arrow, and negative control reactions are indicated by the offset small arrows. The 2 most leftward wells of the first and fifth lanes do not contain any cells and serve as negative controls. Note the high frequency of cells that score positive for both MPO and β-globin. m, marker #6 (Roche Diagnostics, Lewes, UK). (B) Analysis of gene expression in sorted CD34⁺c-kit⁺ AGM cells compared with different cell lines. Several dilutions of each cDNA were amplified to ensure quantitation. The amount shown corresponded to nonsaturated PCR. MEL cells were used as a positive control for globin expression and WEHI-3B for MPO expression, while S17 was used as an example of a nonhematopoietic cell line. The clone of MEL cells used here is HPRT-negative, but the amount of cDNA used was controlled by OD to be equivalent to the other cDNAs amplified here.