miR-3934-5p inhibitor causes inhibited cell proliferation and promotes cell apoptosis. The proliferation and apoptosis of A549 cells was analyzed using an MTT assay and flow cytometry, respectively. (A) Downregulation of miR-3934-5p significantly suppressed the proliferation rate of A549/DDP cells compared with that in the untreated control group and NC group, which was reversed by TP53INP1 siRNA. (B) Cell apoptosis was determined and (C) quantified. Apoptosis was promoted in the miR-3934-5p inhibitor group compared with that in the control and NC groups, which was reversed by administration of TP53INP1 siRNA. *P<0.05 and **P<0.01 vs. NC group; #P<0.05 vs. miR-3934-5p inhibitor group. miR, microRNA; TP53INP1, tumor protein p53-inducible nuclear protein 1; DDP, cisplatin; NC, treated with negative control plasmids; siRNA, small interfering RNA.