After 24 h of normoxic or hypoxic incubation, detached cells in the supernatants and trypsinized adherent cells were counted and the percentage of detached cells calculated. The percentage of viable adherent cells was determined by trypan blue exclusion assay. Mean values ± S.E.M. of at least four independent experiments are shown. Associated significance of hypoxic vs. normoxic cells is indicated (*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001).