Kinetics of DNA damage repair after DNA-PKcs inhibition. A. Results of Western blotting analysis. A reduction of 45% in DNA-PKcs protein level was observed 24 hrs after treatment of cells with 20 μM/μl of IC86621 based on densitometry analysis (software used: ImageQuant V5.1). B-D. Frequencies of γ-H2AX positive foci per cell after 1.0 Gy of gamma rays before and after DNA-PKcsi treatment. E-H. Frequencies of TIF per cell after 1.0 Gy of gamma rays before and after DNA-PKcsi treatment. The results are based on three independent experiments with at least 100 cell nuclei analysed per experiment per point. Error bars represent SEM in B-D and SD in E-H. CJ179 and F01-240 are Artemis defective cell lines whereas GM08399 is a wild type cell line.