Research Paper Volume 2, Issue 10 pp 691—708

Figure 9. Identification of tankyrase-dependent high molecular weight forms of DNA-PKcs. (A) Over-exposed western blot reveals high molecular weight forms of DNA-PKcs, which are dependent upon the PARsylating function of tankyrase 1. A high molecular weight “smear” appears above the primary DNA-PKcs band in the untreated control, which is absent with XAV939 treatment; a lower molecular weight “smear” appears below the primary DNA-PKcs band with XAV939 treatment (degradation products). (B and C) Western blot analysis of same samples (not overexposed) and quantification of DNA-PKcs protein levels following 2, 4 and 6 hour SDS-PAGE run times for DMSO treated controls and XAV939 treated samples to separate high molecular weight forms. The control contains a large amount of DNA-PKcs in a modified, high molecular weight form, as seen by the reduction in DNA-PKcs band intensities over the longer run times (2hr compared to 4 and 6 hr run times; p ≤ 0.001). No significant reduction of DNA-PKcs band intensity over longer run times was observed in XAV939 treated samples (p > 0.05). RE (μ) are an average of two western blot analyses, which were used to calculate SEMs. P-values were determined by a t test to compare two means.