(A) Zymographic analysis on gelatin-containing gels of 72-hour samples of serum-free conditioned medium of fibroblasts derived from MMP-3^+/+ or MMP-3^−/− mice without (lane 1) or with (lane 2) addition of plasmin. (B) Zymography on casein-containing gels in the absence of plasminogen of serum-free conditioned medium of fibroblasts derived from MMP-3^+/+(lane 1) or MMP-3^−/− (lane 2) mice, and of the eluates of MMP-3^+/+ samples without plasminogen (lane 3) or with plasminogen (lane 4) after adsorption with anti–MMP-3 IgG.