Gene expression analysis of CD34⁺CD7⁺⁺CD5⁻ and CD34⁺CD7⁺⁺CD5⁺ proT cell subsets. (A) QRT-PCR analysis of CD34⁺CD7⁺⁺CD5⁻ (proT1) and CD34⁺CD7⁺⁺CD5⁺ (proT2) cells purified by flow cytometric cell sorting from a day-14 HSC/OP9-DL1 coculture. Thymocytes obtained from the Lin⁻ fraction of a human postnatal thymus (PNT) served as a control sample. Transcript levels for the indicated genes (Ccr9 [CD199], Selplg1 [PSGL-1, CD162], Itga2 [α2, CD49b], Itga4 [α4, CD49d], Itga5 [α5, CD49e], and Itgb1 [β1, CD29]) were normalized to human β-actin. These data are representative of 3 independent experiments, with the STD error bars shown corresponding to values obtained from triplicate wells within an individual experiment. (B) Flow cytometric analysis for cell surface expression of CD49d on gated CD34⁺CD7⁺⁺CD5⁻ (proT1, open) and CD34⁺CD7⁺⁺CD5⁺ (proT2, shaded) cells from a day-11 HSC/OP9-DL1 coculture.