Degradation of DNA-PKcs induced by NK314 in ATL cells. (A) Expression of DNA-PK complex in various ATL cell lines and normal CD4⁺ lymphocytes was detected using Western blot analysis. The results with normal CD4⁺ cells were obtained from a different gel in the same experiments with the others. Vertical line(s) have been inserted to indicate a repositioned gel lane. (B) Degradation of DNA-PKcs was determined after treatment with NK314 or etoposide at each time point using Western blot analysis. (C) Contribution of DNA-PK to the inhibition of cell growth by NK314 in ATL cell lines. Cells were treated with etoposide or NK314 with or without NU7026 (NU), a DNA-PK inhibitor. Number of cells was determined with Cell Counting Kit-8. Relative ratio of cell growth was calculated by dividing by the number of untreated cells and expressed as mean ± SD of triplicate analyses.