Fig. 1.

Degradation of p12 subunit by the treatments with genotoxic agents. a–c Optimal sample conditions corresponding to the p12 degradation. The HeLa cells were treated with 150 nM of aphidicolin (a APH treatment), 4 mM of hydroxyurea (b HU treatment), and 1.5 mM of methyl methanesulfonate (c MMS treatment) and then analyzed by Western blot at indicated time, respectively. The numbers shown on the left indicate the positions in kDa protein markers (M). The four subunits of Pol δ (p125, p68, p50, and p12), PCNA, β-actin (as a loading control), and P-Chk1-S345 (as an indicator for ATR/Chk1 signaling activation) are indicated by arrows. The horizontal axis shows the time after individual treatment. d Comparison of protein sample concentrations for 2-DE. The samples at 8 h after treatment with 4 mM of HU were analyzed by “in-gel” determination of extracted protein concentration. Fifty micrograms of total protein each lane calculated from Bradford assay was loaded. 1 Non-treatment as a control. 2 HU treated sample. M protein markers in kDa