Differential up-regulation over time of KRT13 mRNA levels by E2, Tam (trans-hydroxytamoxifen) and Ral. MCF-7 cells were treated with 10 nM E2, 100 nM Tam or 100 nM Ral for 0, 1, 2, 4, 8, and 24 h. RNA was extracted and reverse transcribed, and real time PCR was carried out. Each value represents the mean ± SEM from three separate experiments.