Fig. 3.

E6-AP alters the protein level of ER-α and PR-B protein in the mammary gland. A, Western blot analysis showing relative levels of endogenous ER-α, PR-B, and PR-A in E6-AP^WT, E6-AP^C833S, and E6-AP^KO mice with their WT littermate controls. B–D, The graphs represent the quantification of ER-α, PR-B, and PR-A protein levels from Western blot, expressed as fold increase in E6-AP^WT, E6-AP^C833S transgenic, and E6-AP^KO mice compared with their WT nontransgenic littermates, respectively (mean ± sd, five separate experiments). The differences in ERα and PR-B protein levels between E6-AP^WT or E6-AP^C833S or E6-AP^KO mice and their WT littermates were statistically significant according to Student’s t test (P < 0.05). Relative protein levels were quantitated by NIH ImageJ software. E–G, E6-AP-mediated regulation of ER-α and PR-B protein levels are not controlled at the transcriptional level. Total RNA extracted from mammary epithelial cells of E6-AP^WT, E6-AP^C833s, and E6-AP^KO mice were used in RT-PCR analysis using primers specific for E6-AP, ER-α, and PR-B. Results from three different experiments were averaged and plotted as relative mRNA levels. Error bars refer to mean ± sd of the average quantitated results. E–G, Relative mRNA levels in E6-AP^WT, E6-AP^C833S, and E6-AP^KO, respectively.