Figure 1.

Caspase-2 is localized to the nucleus and Golgi in HeLa cells. HeLa cells (a–f) or HeLa cells stably expressing GFP-golgin-160 (g–i) were fixed, permeabilized, and double-labeled with anti–caspase-2 (a, d, and g) and antigiantin (b and e) or anti-GFP (h). The stained cells were examined by confocal immunofluorescence microscopy. When red (caspase-2) and green (giantin or GFP) images were merged, overlapping red and green pixels appeared orange/yellow (c, f, and i). An identical caspase-2 staining pattern was observed using several different anti–caspase-2 antibodies: affinity-purified MF386, a polyclonal rabbit antiserum raised against the large subunit of caspase-2 (a–c); sc-623, a polyclonal rabbit antiserum raised against an NH₂-terminal peptide of caspase-2 precursor (d–f); and anti-ICH-1_L, an mAb raised against a peptide encompassing residues 225–401 of caspase-2 (g–i). MF388, a second rabbit antiserum raised against the large subunit of caspase-2, also showed identical staining (data not shown). The experiments were repeated on 11 (a–c), 5 (d–f), or 3 (g–i) separate occasions with identical results. Bars: (a–c and g-i) 10 μm; 25 μm (d–f).