Figure 1.

Mitochondrial localization of survivin. (A) Survivin localization in tumor cell lines. Cytosolic (left panel) or mitochondrial (right panel) extracts from the indicated tumor cell lines were analyzed by immunoblotting. MW, molecular weight. (B) Subcellular fractionation of normal tissues. Mitochondrial (M) or cytosolic (C) fractions extracted from normal testis, spleen, and liver or unfractionated HeLa cell extracts were analyzed by immunoblotting. Cox-4 was used as a mitochondrial marker. (C–E) Immunoelectron microscopy. Mitochondrial pellets (C and E) isolated from MCF-7 cells or whole MCF-7 cell extracts (D) were stained with nonimmune IgG (C) or an antibody to survivin (D) followed by colloidal gold-conjugated secondary IgG. Isolated mitochondrial pellets (E) were simultaneously stained with antibodies to survivin (12 nm diameter gold particles) and Smac (6 nm diameter gold particles). Magnification, ×53,000 (C and D), ×104,000 (E).