Figure 6.

The effect of p21 N and C on in vivo DNA repair using electroporation. Histogram showing the role of p21 N and p21 C on DNA repair in normal human fibroblasts GM38A. ¹⁴C-labeled cells were grown to confluence, trypsinized, and harvested. The cells were washed in PBS devoid of magnesium and calcium. Approximately 3 × 10⁵ cells were transferred to a cuvette prechilled on ice in a total volume of 800 μl. GST, p21 N, and p21 C were added to a final concentration of 0.2 μM. The cells were then electroporated at 250 V and 960 F. The cells were immediately chilled on ice, seeded onto culture dishes containing fresh media, and allowed to reattach for 2–4 h. After reattachment, the cells were washed and irradiated with 254 nm UV radiation (30 J/m²). The cells were incubated with medium containing 10 μCi/ml ³H-thymidine for 2 h. The cells were lysed in 0.5% SDS containing proteinase K, precipitated with 5% TCA, spotted on filters, and washed with ethanol and acetone. The samples were then counted in a scintillation counter (n = 2). Error bars represent SEM.