FIG 1.

Cells depleted of MOF are sensitive to replication stress induced by cisplatin, hydroxyurea, or camptothecin. (A and B) Clonogenic survival of MOF-depleted HeLa (A) and U2OS (B) cells treated with the indicated concentrations of HU. (C and D) Clonogenic survival of MOF-depleted HeLa (C) and U2OS (D) cells treated with indicated concentrations of CPT. (E) Clonogenic survival of MOF-depleted HeLa cells treated with the indicated concentrations of cisplatin. The experiments were performed in triplicate, and the error bars represent the standard deviation from three independent experiments. P values: **, <0.01; ***, <0.001. (F) Representative images of metaphase spread of cells with control siRNA (untreated) and MOF-depleted (cisplatin-treated) HeLa cells showing various kinds of chromosomal aberrations. Arrows indicate aberrations. (G to I) Bar graphs show the chromosomal aberrations in control and MOF-depleted HeLa cells treated with either 50 μM cisplatin for 1 h (G), 2 mM HU for 24 h (H), or 250 nM CPT for 6 h (I). “Control” refers to cells that were not transfected with siRNA. The error bars represent the standard deviation from three independent experiments. P values: *, <0.05; **, <0.01. (J) Representative images of cells with R loops in control and MOF-depleted cells. Arrows indicate endogenous R loops detected by S9.6 antibody staining, which specifically detects DNA-RNA hybrids. (K and L) Bar graphs show the quantification of the percentages of cells showing endogenous R loops in control and MOF-depleted HeLa (K) and U2OS (L) cells. The error bars represent the standard deviation from three independent experiments. P values: **, <0.01; ***, <0.001.