Gene expression analysis using RT-PCR. Lanes 1, negative control; lanes 2, RNA from EB-PE cells grown in bFGF and Epo; lanes 3, RNA from EryP cells. EryP colonies were obtained by replating day 4 EB cells into methylcellulose cultures with Epo. The resulting EryP colonies were pooled and RNA was extracted. The amplified DNA sizes are indicated on the right. β-actin is shown as a control.