Senescence-associated loss of histones is V-ATPase dependent. (A) Bafilomycin A1 (BafA1) blocks the loss of nuclearhistone H3content in cells undergoing OIS. BafA1 was added to cells at 50 nM on day 5 after RASG12V induction. Cells were harvested 24 h later, and stained for histone H3. Bars, 10 µm. (B) Quantitative histone H3immunofluorescence in cells from A. Single representative experiment out of three repeats. 