Expression of embryonic ζ- and εy-globins in compound mutant mice. (A,C) QRT-PCR analysis of mouse ζ- and εy-globin, absolute expression levels calculated relative to expression of mouse α-globin. (B,D) Expression levels relative to those observed in control mice of the same age group; expression of α-globin was used for normalization. N = 3 to 5 for each genotype and time point. Note logarithmic scales. *P < .05 between mutant and control groups; P < .05 between mutant groups is indicated by a color-matched asterisk.