Survivin expression in primary megakaryocytes. Mouse primary megakaryocytes were treated with or without 20 μM proteasome inhibitor MG132 for 6 hours. Cells at prophase were stained with DAPI (blue; i), anti–Aurora-B/AIM-1 antibody (red; ii), or anti-survivin (green; iii). Triple staining (iv). Shown are representative images captured as described in “Materials and methods.” (A) Polyploidizing megakaryocyte with ploidy of 16N at prophase. (B) MG132-treated polyploidizing megakaryocyte with ploidy of 8N at prophase. In approximately 100 megakaryocytes examined (treated or not treated with MG132), survivin was not detected. Similar results were noted for cells at anaphase (not shown). (C) Only one 8N megakaryocyte at prophase displayed survivin after MG132 treatment. Original magnification, × 1500.