Figure 2. A slowdown of Dox-induced aging via the overexpression of miR-199a-3p. (A) Expression of miR-199a-3p was quantified by qRT-PCR. *P < 0.05 versus the miR-199a-3p mimic in repeated-measures ANOVA, n = 6 per group. (B) Percentages of cells in the three phases of the cell cycle determined by flow cytometry. (C) Cellular proliferation was measured by the CCK-8 assay. (D) SASP factor protein levels quantified by Luminex of the medium. The medium was collected from such cells as follows: transfection with the miR-199a-3p mimic or miR-NC mimic, followed by treatment with Dox. The untreated cardiomyocytes were used as control. (E) The percentage of senescent cells was calculated. (F) Representative images of SA-β-gal staining (senescent cells are stained green). Scale bars, 20 μm. (G) Telomere length was detected by qRT-PCR. (H) Telomerase activity was determined using a telomerase repeat amplification protocol (TRAP). *P < 0.05 versus control; ▲P < 0.05 versus Dox + miR-199a-3p mimic in repeated-measures ANOVA, n = 6 per group.