Bortezomib-treated mice, platelet counts, and megakaryocytes. (A) Platelet counts from BALB/c mice after intravenous administration of bortezomib 2.5 mg/kg. (B) Absolute numbers of megakaryocytes (1 femur, 2 tibiae) in different ploidy subsets from mice killed 4 or 15 days after receiving bortezomib 2.5 mg/kg. Untreated mice served as baseline controls and there were 4 to 5 mice per group. Error bars represent standard deviation. (C-E) Bone marrow sections showing megakaryocyte cells. (C) Untreated control. (D) Four days after bortezomib 2.5 mg/kg. (E) Fifteen days after bortezomib 2.5 mg/kg. Original magnifications, × 200; inset, × 600.