Day 21 lung hydroxyproline concentrations in bleomycin-injured transgenic mice. PAI-1^−/− mice that transgenically express PAI-1(V+P+), PAI-1(V+P-) or PAI-1(V-P+) off of the preproendothelin promoter were treated with intratracheal bleomycin (1.15 μg/kg in 50 μL of sterile PBS) on day 0. Groups of WT and PAI-1^−/− mice were also treated with bleomycin. A control group of WT mice was left uninjured and was used to establish a baseline level of lung collagen. On day 21, lungs were harvested from each animal and the concentration of hydroxyproline was measured. Hydroxyproline results from the 2 separate studies were pooled and are normalized to the extent of fibrosis measured in the bleomycin treated WT which is set at a 100% increase in lung collagen above baseline ± SEM. N = 6-8 mice per time point. Groups are compared with a 1-way ANOVA with Newman-Kuels posthoc multiple comparison test.