Figure 3. Expression levels of 53BP1, SETD8 and H4K16ac. (A) Western blot analysis of c-NHEJ and HR factors. Basal levels of (i) high and (ii) low molecular weight DNA repair proteins. Stain-free technology and/or Integrin β1 (ITGB1) have been used for sample normalization and U2OS cells were used as a positive control. (B, D) RT-qPCR analysis of 53BP1 (B) and SETD8 (D). GAPDH and β-actin were used as reference genes (* p < .05, nsp > .05; t-test). (C) H4K16ac analysis. (i) Immunofluorescent labeling of cell nuclei (DAPI, blue), H4K16ac (A488, green) and pericentrin (A594, red). Representative G1 cells with high or low H4K16ac fluorescence intensity are shown. Scale bar = 10 μm. (ii) Fluorescence intensity of H4K16 acetylation in G1 cells (1 perincentrin signal). Each dot corresponds to one cell and the mean and quartiles are indicated (a≠b≠c p < .05; n = 40 cells/donor; Kruskal–Wallis + Dunn).