The effects of PDGF-bb and 20% serum on cell proliferation and miR-665 expression in VSMCs. A. PDGF-bb (30 ng/ml) significantly promotes VSMCs proliferation at 24, 48 and 72 h after treatment, as measured by CCK-8 assay. B. 20% serum significantly promotes VSMCs proliferation at 48 and 72 h after treatment, as measured by CCK-8 assay. C. The expression of miR-665 as measured by qRT-PCR was down-regulated at 72 h post PDGF-bb (30 ng/ml) treatment. D. The expression of miR-665 as measured by qRT-PCR was down-regulated at 72 h post 20% serum treatment. Data represents the mean values of three independent replicates ± SEM; significant differences relative to control group were shown as *P<0.05, **P<0.01, ***P<0.001.