Interaction of MYH with ATR or TopBP1 increased following ETP treatment. (A) ATR or TopBP1 interact with MYH increases following treatment with ETP. Cells were treated with 25 μM ETP for 48 h. Cells were lysed and total cell lysates were used for co-IP with MYH antibody. IP samples were analyzed by western blotting with ATR or TopBP1 and MYH antibodies. β-actin was used as a loading control. (B) ATR or TopBP1 and MYH co-localized following treatment with ETP. Cells were cultured overnight on coverglass bottom dishes, then treated with 25 μM ETP for 48 h, and fixed with 4% paraformaldehyde and permeabilized with 0.1% Triton X-100 in PBS. Cells were then stained with antibodies against ATR or TopBP1 (FITC; yellow), MYH (Alexa®488/Green) and To-pro®3 (Red). IB, immunoblot; ATR, Rad3-related protein; TopBP1, topoisomerase-binding protein-1; MYH, MutY homolog; IP, immunoprecipitation; Ab, antibody. ETP, etoposide; PBS, phosphate-buffered saline; FITC, fluorescein isothiocyanate.