Compared with parental HEL and SET-2 cells, BETi-P/R cells exhibit greater nuclear expression of TCF7L2 and TBL1 and sensitivity to treatment with the β-catenin antagonist BC2059 or BET-PROTAC. (A) SET-2-OTX P/R, SET-2, HEL-OTX P/R, and HEL cells were treated with 100 nM BC2059 for 16 hours. Following this, cells were cytospun onto glass slides and stained with antibodies for confocal microscopy (original magnification ×100). Representative images are shown for each condition. (B) SET-2-OTX P/R, SET-2, HEL-OTX P/R, and HEL cells were treated with the indicated concentrations of BC2059 for 96 hours. At the end of treatment, the percentage of annexin V–positive, apoptotic cells were determined by flow cytometry. (C-D) Immunoblot analysis of SET-2, SET-2-OTX P/R, HEL, and HEL-OTX P/R cells treated with 100 nM BC2059 or 250 nM ARV-825 for 16 hours. (E) SET-2-OTX P/R, SET-2, HEL-OTX P/R, and HEL cells were treated with the indicated concentrations of ARV-825 for 48 hours. Following this, the percentage of annexin V–positive, apoptotic cells was determined by flow cytometry.