<p>MSCs-<i>TetR</i>/<i>Amelx</i> were cultured in the growth medium in the presence (<b>+</b>) or absence (<b>-</b>) of Dox for 24–72 hours. Inducible expression of the <i>Amelx</i> gene was detected by RT-PCR (<b>a</b>) and western blot (<b>b</b>) analyses. GAPDH was used as a loading control. (<b>c</b>) MSCs-<i>TetR</i>/<i>Amelx</i> were cultured in the osteogenic induction medium in the presence (+) (black bars) or absence (-) (white bars) of Dox for 17 days in four different conditions. (Condition I: day 0–17 Dox-; Condition II: day 0–14 Dox-, day 15–17 Dox+; Condition III: day 0–14 Dox+, day 15–17 Dox-; Condition IV: day 0–17 Dox+). Expression of <i>Amelx</i> was determined by quantitative real-time RT-PCR analysis. Significant differences (*<i>P</i><0.01: ANOVA with Tukey’s multiple comparison test: n = 4) within each condition are shown.</p
