Inhibition of Src or Chk1 diminishes formation of actin patches. (A and B) Cells were transfected with negative siRNA (control), siSrc, or siChk1. Lamin B–negative (A) or γ-H2AX–positive micronuclei (B) are indicated by arrowheads. (C) Frequency of cells exhibiting lamin B-negative or γ-H2AX–positive micronuclei. Error bars show the SD from the mean from three independent experiments. A minimum of 150 cells was analyzed per experiment. (D) Cells were transfected as in A or treated with PP2 for 5 h. Broken DNA bridges are indicated by dotted arrows, and the bases of the intercellular canals are indicated by solid arrows. Relative actin patch intensity values are shown. Insets show 3× magnification of the canals bases. Bars, 5 µm. (E) Actin patches intensity. Relative green fluorescence intensity from D is shown, and values in control were set to 1. Error bars show the SD from the mean. n = 30 cells from three independent experiments. ***, P < 0.001 compared with the control. Statistically significant differences were determined by ANOVA and Student’s t test. (F) Western blot analysis of total α-tubulin and actin.