Figure 4.

The nuclear foci enriched in 20S proteasome-α7-CFP complexes correspond to the NS. (A) U₂OS-tTA-α7-CFP were fixed 48 h after α7-CFP induction, permeabilized, and stained with a mAb directed against the phosphorylated NS protein SC35 (red) and with DAPI dye (blue). α7-CFP fluorescence is in green for easier codetection (α7-CFP/SC35 image). Wide-field of individual detection and overlay images are presented (63× objective). Bar, 10 μm. (B) Forty-eight-hour–induced U₂OS-tTA-α7-CFP cells, untreated or treated with DRB (100 μM) or actinomycin D (10 μg/ml) for 2 h before fixation, were stained with anti-SC35 (red); α7-CFP expression was directly visualized by CFP fluorescence (cyan; 100× objective). Bar, 10 μm.