Inhibition of redox activity of Ape1, but not base excision repair (BER) activity of Ape1, reduces BL-CFC and Ery-P formation. (A) In the BL-CFC assay, day-3 EB cells were treated with VEGF, SCF, and various doses of E3330 (0 to 100 nM) or MX (0 to 10 μM) as indicated in the culture. After 4 days of culture, the BL-CFC colonies were scored; the number is shown. Results shown are representative of 3 independent experiments, each performed in triplicate. Mean values significantly different from control cells (untreated or treated with DMSO) are indicated. *P < .05; **P < .01. (B) In Ery-P assay, day-6 EB cells were treated with Epo and various doses of E3330 (0 to 100 nM) or MX (0 to 10 μM). After 7 days of culture, Ery-P colonies were scored. Results shown are representative of 3 independent experiments, each performed in triplicate. Mean values significantly different from control cells (untreated or treated with DMSO) are indicated. *P < .05; **P < .01. Bars represent mean ± SD of triplicate experiments.