Cell migration through type-I collagen is enhanced under hypoxic conditions: effect of matrix metalloproteinase inhibition. Rheumatoid arthritis fibroblast migration was investigated under normoxic (21% oxygen) and hypoxic (1% oxygen) conditions over a 48-hour culture period. The top chamber was coated with porcine type-I collagen, followed by the addition of 20,000 fibroblasts per well. The chambers were subsequently placed in a 24-well culture plate, with the lower chambers containing DMEM plus 10% FCS. A universal MMP inhibitor (GM6001; 10 μM) was added to both the bottom and top chambers of selected inserts, before exposure to either normoxia or hypoxia. Migration from six different patients, assayed in triplicate, is shown. Data presented as the mean ± standard error of the mean and were analysed by repeated-measures one-way analysis of variance, with Bonferroni's post hoc test for multiple comparisons: **P < 0.01, ***P < 0.001.