Effect of miRNAs on endogenous GHR mRNA and protein expression in MCF7 cells. A, Expression of human total GHR mRNA in MCF7 cells transfected with 50nM of each mimic. The data are presented as mean ± SE of 4 individual experiments for all but miR-202 (n = 5); duplicates were assayed within each experiment. Statistically significant differences between the control and miR-treated cells were found for miR-129–5p, miR-202 (***, P ≤ .001), and miR-142–3p (**, P ≤ .01), whereas miR-16 had no effect (not significant [ns]). B, GHR protein levels were determined by Western blot and normalized to calnexin. Normalized values are shown relative to the negative mimics control treatments (100%). Composite results for n = 4 individual experiments (mean ± SE) showing statistically significant differences between negative control and miR-treated cells: *, P ≤ .05 for all treatments. C, Representative Western blot of GHR and calnexin protein levels in MCF7 cells after transfections with 50nM miR-129–5p, miR-142–3p, miR-202, and miR-16 mimics.