Differential effect of NTAPP on different types of human cells.

<p>(A–F) (A, B) HeLa, (C, D) adipose tissue-derived stem cells (ASCs), and (E, F) IMR90 cells were exposed with 5 V input NTAPP for 30 s every h for 10 times, and cell viability was evaluated at each indicated exposure frequency. Incubation time indicates the time after initial exposure to NTAPP. The 24-h incubation sample was prepared with 10 repetitive NTAPP exposures followed by further incubation for 15 h. (A, C, E) The relative percentages of viable cells are shown comparing the initial cell number prior to exposure and incubation as 100%. Viable cells were quantified with MTT assays, and data are shown as mean ± SEM from three independent experiments. <i>p</i><0.05 (*) and <i>p</i><0.01 (**) indicate significant differences compared with the control condition. (B, D, F) For the same NTAPP-exposed samples of (A), (C), (E), respectively, γ-H2AX, caspase-3, cleaved caspase-3, PARP, and cleaved PARP were assessed by western blot analyses. Actin is shown as a loading control.