Zymographic and reverse zymographic analysis of BAL fluid. (a) Zymographic analysis of wild-type and null BAL at 2 and 5 months of age. No differences in MMP-9 (105 kDa) or MMP-2 (72 kDa) abundance or activation (asterisks) were noted. Incubation of a sample lane with a synthetic MMP inhibitor, GM6001, identified which bands represented MMP gelatinolytic activities. (b) Reverse zymographic analysis demonstrated there was no compensation in null BAL by upregulation of either TIMP-1 or TIMP-2. (c) Parallel Coomassie-stained SDS-PAGE gel revealed the bands in b were gelatin-protecting bands and not Coomassie-staining bands in the BAL. Panel c also shows approximately equal loading between samples.