Human CD34+ HSPCs were treated with vehicle (VH) or TCDD (0.01, 0.1, 1 or 10 nM) on day 0. Cells were cultured for up to 28 days and harvested at the specified time points. The mRNA levels of PAX5 were assayed by real-time quantitative PCR and were normalized to 18s ribosomal RNA. Data are presented as mean ± SE of triplicate measurements. * p <0.05, **p <0.01, ***p <0.001, compared to the VH using a two way ANOVA with Bonferroni posttest after logarithmic transformation. Data are representative of three independent experiments with similar results.