VCP/p97 expression during cell cycle distribution of synchronized U937 cells. A. U937 cells were separated by centrifugal elutriation and cell lysates of the appropriate fractions were analyzed by Western blot using an anti-VCP/p97 and an anti-phosphotyrosine antibody, respectively. Expression of β-actin was used as a loading control. B. The cell cycle distribution of the appropriate elutriated cell fractions were analyzed by flow cytometry and histograms were generated by the FloMax software. C. Quantification of the cell cycle distribution of the elutriated fractions and the percentage of the distinct cell cycle phases was gated and calculated using the MultiCycle software.