FIG. 6.

Expression of flk1 and HoxB5 mRNA in differentiating embryoid bodies. (A) To assess the time course of HoxB5 and flk1 mRNA expression, embryoid bodies were differentiated for 2, 4, 6, 8, or 10 days, and total RNA was extracted from the cells at the indicated times. The specific genes were detected by RT-PCR. GAPDH served as an RNA integrity and normalization control. (B) To determine whether HoxB5 is expressed in flk1⁺ populations, embryoid bodies were differentiated for 4 days and then sorted into flk1⁺ and flk1⁻ populations. Total RNA was isolated from 10⁶ sorted cells from each population. RT-PCR analysis demonstrated expression and relative enrichment of HoxB5 mRNA in the flk1⁺ cell population.