Globin gene expression in embryos with combined deficiency of NF-E2 and Nrf-2. Compound heterozygous mice were mated and total RNA was extracted from the fetal livers of day 13.5 to 15.5 embryos. Genomic DNA was extracted from the heads of the embryos and analyzed for NF-E2 and Nrf-2 genotype. β- and α-globin and β-actin expression was analyzed by ribonuclease protection assay (1 μg RNA). The size of the protected transcripts was 245, 128, and 150 bp, respectively. As indicated at the top, comparisons were made between samples from the same litter. A standard curve was performed with RNA from murine erythroleukemia cells for each of the probes.