Analysis for markers of differentiated tissues. Ethidium bromide–stained gels of RT-PCR amplification using various marker genes of differentiation. RNA was extracted from EBs derived from WT ES cells (WT) and from 2 different G6pdΔ ES cell lines (G6pdΔ1 and G6pdΔ2). Number of days in culture is given at the top. Amplified Hprt is shown as a positive control.