2.14 Western blot analysis
Protein samples from the cells of split-GFP assay (incubation time was prolonged to 72 h) were prepared by dissolving the cultures directly in 2X SDS sample buffer and analyzed by western blot analysis. The primary antibodies used were as follows; rabbit anti-cleaved caspase-3 and caspase-9 (Cell Signaling #9664 and #52873), and mouse anti-GAPDH (Abcam, ab8245). We used secondary antibodies conjugated with horseradish peroxidase (KPL, USA), and developed the blots using ECL Western Blotting Substrate (Thermo Fisher Scientific, USA). Images of original uncropped western blots were provided (Fig. S4).