p21-antisense increases the relative abundance of CD34⁺38^– cells (in transduced CD34⁺ cord blood cells without alteration in apoptotic rate). CD34⁺ cord blood cells were transduced with p21-antisense (p21-AS-V) or the control vector (GFP-V) and maintained in culture. (A) The ratio of total CD34⁺38^– cells in the p21-AS-V versus control over time is shown. Horizontal line indicates equivalence. (B) Apoptosis assays were performed 4 days following transduction using AnnexinV and 7-AAD. Chart shows the percentage of AnnexinV-positive cells in the CD34⁺GFP⁺7AAD^– subpopulation (n = 13) (left chart) and in the CD34⁺38^– GFP⁺7AAD^– subpopulation (right chart).