Transfection of HPMA-oligolysine-oligohistidine polyplexes in HeLa and COS-7 cells with chlorpromazine, genistein, or amiloride. (A) Transfection efficiency and (B) protein content of HeLa cells, and (C) transfection efficiency and (D) cell viability of COS-7 cells transfected with polyplexes formulated with statistical (pShi0, pShi2) or diblock (pB0, pB1) and DNA (1 μg) at N/P 5 in the presence of 10 μg/mL chlorpromazine, 50 μg/mL genistein, or 25 μg/mL amiloride under serum-free conditions. Data are presented as the mean ± S.D., n = 4, and representative of four independent experiments. (*) p < 0.05, as determined by a two-tailed, unpaired Student’s t-test with unequal variance.