reduces apoptosis of HaCaT cells after X-ray irradiation. (A) HaCaT cells were treated with PBS, SOD1 or TAT-SOD1 5 h prior to irradiation with 20 Gy. Cells were collected 48 h after irradiation, stained with Annexin V-FITC and propidium iodide-TRITC and analyzed by flow cytometry. (B) Agarose gel electrophoresis of DNA extracted from HaCaT cells. (C) Western blot analysis of apoptotic marker proteins in HaCaT cells exposed to ionizing radiation. Cell extracts were subjected to 12% SDS-PAGE and immunoblotted with antibodies against cleaved Caspase-3, Bcl-2, or Bax. β-Actin was used as an internal control.