Quantitative RT-PCR analyses of EPO modulation of Irs2, Foxo3a, Trb2, Trb3, Bim, Pim1, Pim3, and S3G expression. (A) For each of these (anti)apoptotic factors, multifold modulation by EPO was confirmed by RT-QPCR within Kit^posCD71^highTer119^neg erythroblasts as exposed to EPO for 90 minutes. Values are means plus or minus SD for n = 3 independent samples. (B) For each factor, time courses of modulation by EPO also were analyzed. Here, Kit^posCD71^highTer119^neg erythroblasts were isolated, cultured for 6 hours in the absence of hematopoietic cytokines, and exposed to EPO (2.5 U/mL). At the indicated intervals, RNA was prepared, reverse-transcribed, and used in quantitative PCR analyses (vs beta-actin as a normalizing control). For an independent sample set, time course analyses were repeated. Results are illustrated for 2 such analyses as mean fold modulation due to EPO for each EPO-modulated candidate survival factor.