miR-15a/16 and miR-34a act synergistically to induce cell cycle arrest. (A) Cell cycle analysis of A549 cells transfected with pre-miR-34a and/or pre-miR-15a/16 under non-saturating conditions. Precursors were supplemented with precursor control to yield a total concentration of 2.5 nM per transfection. *, transfection with 2.5 nM precursor control. Cells were treated for 18 h with nocodazole beginning 24 h post-transfection (n = 3). (B) Cell cycle analysis under saturating conditions. A549 cells were transfected with 20 nM precursor or precursor control or co-transfected with 10 nM pre-miR-34a and 10 nM pre-miR-15a/16 and treated for 18 h with nocodazole beginning 24 h (left panel) or 48 h (right panel) post-transfection (n = 3).