Figure 4A: Effects of the ultrasound treatment on transfection efficiency of PDMAEMA-DNA complexes at various ratios. Cells were treated with PDMAEMA-DNA complexes and ultrasound or without (normal group) a low energy ultrasound for 10 sec and 9 cycles. Values are expressed as Mean ± SD in triple experiments. Statistics are shown for cells treated with ultrasound compared to untreated cells at ratios of 5/1 (p<0.01), 3/1 (p<0.05) and 2/1 (NS; not statistically different).