Effect of MMP-12 deficiency on BAL leukocyte recovery. BAL was performed on transgene^– and transgene⁺ CC10-rtTA-IL-13 mice with wild-type and null MMP-12 loci that had been randomized to normal water or dox water. Total cell recovery (a) and the recovery of macrophages (b), lymphocytes (c), neutrophils (d), and eosinophils (e) are illustrated. Each value represents the mean ± SEM of a minimum of four animals (*P < 0.01).