Figure 2. Depletion of Ku70/80 in CCL75.1 cells induces transient p53 activation. The levels of p21, p53, and p53 phosphorylated at serine 15 were assessed by Western blotting in extracts prepared from CCL75.1 cells collected either before, or 3 to 6 days after addition of DOX. Tubulin serves as a loading control. Western blot analyses were performed with antibodies against p53, p53-phosphoserine15, p21, and tubulin.