NF-E2 expression in Nrf-2 (+/−) and Nrf-2 (-/-) fetal liver cells. NF-E2 was immunoprecipitated from fetal liver cells of day 13.5 to 15.5 embryos as described in Materials and Methods. Four fetal livers are shown from the embryos of one litter. Fourteen fetal livers from two litters were studied, and these results are representative. Nrf-2 genotype is indicated at the top with preimmune (PI) and immune (I) antisera. The extracts were serially immunoprecipitated with anti-Sp1 antibody (Santa Cruz) as a control. Sp1 peptide was added to one reaction as a negative control.