Effects of MEG3 on cell proliferation in vitro . (A) Analysis of MEG3 expression levels in SPC-A1 and A549 cells transfected with PCDNA-MEG3 or empty vector by qRT-PCR. (B) MTT assay was performed to determine the proliferation of SPC-A1 and A549 cells. Data represent the mean ± S.D. from three independent experiments. (C) Colony-forming growth assays were performed to determine the proliferation of SPC-A1 and A549 cells. The colonies were counted and captured. (D) The bar chart represented the percentage of cells in G0/G1, S, or G2/M phase, as indicated. All experiments were performed in biological triplicates with three technical replicates.*P < 0.05, **P < 0.01.