Bcl-2 inhibition induces Bax/Bak oligomerization in CTCL cell lines depending on their Bcl-2 activity. (A) Complex formation of Bax and Bak was determined by PLA in SeAx cells either treated with ABT-199, DMF or the combination of both drugs, as indicated. Vehicle treated cells served as control. Bax/Bak association is depicted by green fluorescence; blue fluorescence indicates nuclear staining with Hoechst dye; shown are representative immunofluorescence analyses from z-stacks. Original magnification ×400. (B) Quantification of mean fluorescence intensities of PLA signals (n = 4). *P < .05 from untreated control.