Effect of 3F plasmid in combination with Pax4 overexpression on insulin secretion in response to glucose. Transfected cells were stimulated either with low-glucose or high-glucose, and insulin secretion was determined by ELISA. Experiments were performed 4 days after transduction. Values are expressed as the mean ± standard deviation (n=5). ***P<0.001 vs. low-glucose group; #P<0.05, ###P<0.001 vs. 3F group. Groups: EGFP, cells transfected with EGFP plasmid; 3F, cells transfected with Pdx1/MafA/Ngn3 plasmid; Pax4, cells transfected with Pax4 plasmid; 3F/Pax4, cells transfected with Pdx1/MafA/Ngn3 plasmid and Pax4 plasmid. Pdx1, pancreatic and duodenal homeobox 1; MafA, MAF bZIP transcription factor A; Ngn3, neurogenin 3; Pax4, paired box 4; EGFP, enhanced green fluorescence plasmid.