RT-PCR analysis of the expression of SDF-1 and CXCR4 by CD34⁺ cells. (A) Expression of CXCR4 and SDF-1 in freshly isolated CD34⁺ cells from UCB, BM, and G-CSF MPB. The RT-PCR was performed as indicated in Materials and Methods. GAPDH is shown as a control. (B) RT-PCR analysis of CXCR4 and SDF-1 expression in sorted CD34⁺/CD38⁻ and CD34⁺/CD38⁺ cells from UCB, BM, and MPB.