Bone marrow p19^INK4D knockout megakaryocytes have an increased ploidy. Bone marrow megakaryocyte ploidy from WT, p19^INK4D+/−, and p19^INK4D−/− was measured after labeling with an anti-CD41 antibody and propidium iodide (PI) staining using flow cytometry. More than 10 × 10⁶ cells were recorded and the ploidy was measured in a CD41-high gate. (A) One representative experiment is shown. (B) The mean ploidy of 4 experiments is illustrated. In all experiments, the modal ploidy increased from 16N in wt MKs to 32N in p19^INK4D+/− MKs and to 64N in p19^INK4D−/− MKs as shown in panel A.