Immunoblot of Rad53 mobility shift assay in cells treated with 0.02% MMS expressing either DPB11BRCT3/4 alone or the BRCT3/4-SGS1 chimera. Dilution assay of wild-type, ddc1Δ, or ddc1-T602A cells expressing BRCT3/4-SGS1 in the presence of 0.005% MMS. 