Effect of transiently expressed Let-7a mimic on cellular STAT3 pools. SiHa cells (2 × 105 cells) transiently-transfected with indicated concentrations of Let-7a mimic for 48 h were examined for viability, intracellular Let-7a and STAT3 expression. A. Graph showing cell viability by MTT assay following transient transfection with Let-7a mimic at indicated doses. Values are mean ± SD of triplicate cultures with respect to untreated control. *p value <0.05. B. Representative gel photograph showing increased intracellular levels of Let-7a in treated cells (upper panel). Total RNA isolated from treated SiHa cells was examined for Let-7a by qRT-PCR. Expression of U6 similarly amplified in parallel was used as input control (lower panel). M: ΦX 174 HaeIII-digested molecular weight markers; UT-untreated cells. C &D. Dose-dependent effect of transiently-transfected Let-7a on STAT3 levels. Cellular proteins isolated from Let-7a mimic-treated SiHa cells were examined for levels of STAT3 protein by immunoblotting (C). Blots were stripped and re-probed with β-actin antibody as loading control. Specific STAT3 bands were evaluated densitometrically and normalized against untreated control (UT). Let-7a fold change was calculated with respect to control by 2-ΔΔCt method. Graph showing mean ± SD of the fold change in expression of intracellular Let-7a and STAT3 protein after treatment with Let-7a mimic in three independent experiments (D). *p value <0.05 compared to untreated cells.