Inhibition of hypoxia-induced uPAR expression by carbon monoxide. HTR-8/SVneo cells were incubated for 24 hours under standard (20% O₂) or hypoxic (1% O₂) conditions, or hypoxic conditions in the presence of 20% carbon monoxide. The expression of uPAR was then assessed by flow cytometry using MoAb 3937. Carbon monoxide inhibited the hypoxia-induced expression of uPAR by 56%. Data represent the mean ± standard error of four independent experiments.