Fig 1: H3K4 Methylation by SETD1A Protects against CHD4-Mediated Fork Degradation(A) U-2-OS cells were transfected with the indicated siRNAs for 72 hr, exposed to 50 ng/mL MMC for 24 hr, and immunostained with antibodies to RAD51, and focus formation was analyzed by fluorescence microscopy. Representative images are shown (right). Scale bars, 10 μm.(B and C) Cells were transfected with control siRNA or those targeting SETD1A and CHD1 (A) or SETD1A and CHD4 (B), exposed to HU, and treated as described in Figure 3. Plots in (B) and (C) amalgamate data from the same experiments; arrows indicate mean ratios.(D) Micronucleus formation in cells from (A) was analyzed by fluorescence microscopy.(E) Quantification of PLA signals between EdU and RAD51 in U-2-OS cells transfected with the indicated siRNA. Where denoted, cells were exposed to 4 mM HU for 5 hr.In all cases, plots represent mean data ± SEM from 3 independent experiments. ∗p < 0.05 and ∗∗∗p < 0.001. See also Figure S5 and Table S1.