Effect of CO donor on surface expression of VLA-4 (CD49d/CD29 heterodimer). U937 cells were treated with vehicle (DMSO, control), and CO donor (150 μM CORM-2) for 30 min at 37°C. Next, cells were placed on ice and stained with primary labeled anti-CD29 and anti-CD49d antibodies, or the isotype control. A. Histograms of anti-CD29 and anti-CD49d antibodies are shown in black, and the isotype control is grey. B. Bar graphs of mean channel fluorescence (MCF) ± SEM (n =5) for unstained cells (autofluorescence), nonspecific binding to cells (isotype control), cells treated with vehicle (DMSO), and cells treated with CORM-2 are shown (10,000 gated events for each sample were collected). One representative experiment of three experiments is shown. * indicates means are significantly different (P <0.05) as estimated by the unpaired t test analysis using GraphPad Prism software.