Rat strain-specific effects of 17β-estradiol on mRNA expression. RNA was isolated from mammary glands of ACI and BN rats, treated with E2 for 12 weeks. Expression of mRNAs encoded by 8 genes of interest was quantified using the ΔΔCq PCR-based method. Each data bar represents the level of the indicated mRNA normalized to the level of β-actin mRNA (mean ± SEM, n = 3. *, p < 0.05). The differences observed upon comparison of expression of these 8 mRNA in mammary glands from E2 treated ACI and BN rats were concordant with differences in expression observed upon microarray analysis.