Fig. 5.
REA is required for the maintenance of differentiated lobuloalveolar structure. A, Representative photograph of pups nursed for 20 d by REAf/f or REAf/f WAP-Cre (WC) mothers. B, The body weights of pups nursed by REAf/f or REAf/f WAP-Cre mice during the first 20 d of postnatal development. The dam's genotype has a significant effect on the body weights of pups, with reduced weight gain of the pups nursed by REAf/f WAP-Cre dams (GLM, F1,358 = 2280; P < 0.0001). GLM with repeated measures ANOVA. The data are mean ± sem (n = 20 per group). C, Representative hematoxylin- and eosin-stained mammary gland sections from REAf/f and REAf/f WAP-Cre at different stages of pregnancy, lactation, and involution. Magnification, ×40. D, qRT-PCR analysis of genes involved in milk protein expression (casein-α, casein-β, casein-κ, and WAP), lactose synthesis (α-lactalbumin), and milk lipid secretion (butyrophilin) at different stages of pregnancy (d 8 and 18) and lactation (d 2, 14, and 19). The data are mean ± sd (n = 10 per group), and mRNA levels are illustrated as relative expression normalized to 36B4 by wild-type P8. E, Mammary gland lysates were analyzed by immunoblotting for REA and phospho-Stat5. ERK2 served as a loading control. #, P < 0.05 vs. wild type.