Figure 3. Cdk4-independent DSBs formation in 31FR-31NR cells (A) Cell cycle distributions for HeLa cells with either control siRNA (siControl) or Cdk4 siRNA (siCdk4). Percentages of G1-, G2/M- and S-phase cells are shown with the standard deviations in parentheses in the lower panel. (B) Western blotting results for Cdk4, γ-H2AX and actin in 0FR and 31FR-31NR cells derived from HeLa cell line. Cell extracts were prepared at 48 h after transfection with either control siRNA or Cdk4 siRNA. (C) Western blotting results for γ-H2AX and actin in the 0FR and 31FR-31NR cells derived from HeLa cell line. The cells were treated with 1.9 μM Cdk4-I for 24 h.