Selinexor reduced blood cell counts in mice and the number of MKs in the bone marrow. (A) CD1 mice (N = 4 per cohort) were treated with saline vehicle (gray bars) or selinexor (red bars, 20 mg/kg by mouth, every other day, three times per week) for 3 weeks. Platelet counts were done at the end of each week of treatment. (B) Quantification of MKs in femur bone marrow sections. Images spanning 1 complete longitudinal cross section of the entire femur from 2 femurs per mouse were used for quantification. Each mouse (2 femurs) was considered 1 biological replicate. N = 4 per cohort; ***P < .001. (C) Representative hematoxylin and eosin images (×20) and high (×20) and low (×10) magnification immunofluorescence staining for von Willebrand factor showing MKs in bone marrow. N = 4 mice per cohort; bars represent 10 μm.