Sox6^–/– erythroid cells show defects in hemoglobinization and cytoskeleton integrity. (A) Coomassie blue–stained SDS-PAGE of lysates from control (C) and Sox6^–/– (N) fetal liver cells cultured on fibronectin with 2 U/mL Epo for 6 to 48 hours. All lanes were loaded with lysate amounts corresponding to equal cell numbers. The picture shows the section of the gel at the 15-kDa level, where the most intense protein band was seen, as expected for globin chains. (B) FACS analysis of hemoglobin level in control and Sox6^–/– erythroid cells cultured on fibronectin with 2 U/mL Epo for 24 hours. The mean cell hemoglobin intensity is indicated. (C) Quantification of relative α-globin and β-globin RNA levels in control and Sox6^–/– erythroid cells cultured on fibronectin with 2 U/mL Epo for 0 to 48 hours. (D) Globin chain analysis in E15.5, E16.5, and E19.5 Sox6^–/– and control fetuses. The migration level of the primitive Eγ globin chains, definitive β-globin chains, and α-globin chains is indicated. (E) Ghost analysis of control and Sox6^–/– RBCs at P0 and P7. Samples were loaded in amount corresponding to similar cell numbers. (F) Quantification of α1-spectrin and protein 4.1 RNA levels in control and Sox6^–/– erythroid cells. The experiment was done and data are presented as described in panel C. (G) Histograms of TER119 FACS analysis of blood samples from E18.5 and P7 mice. The mean with standard deviation of TER119 fluorescence is indicated for 3 control (C) and 3 Sox6^–/– (N) littermates. The differences in absolute values between E18.5 and P7 samples are due to experimental variability rather than differences between mouse ages.