Can degrade fibronectin, gelatins of type I, III, IV, and V; weakly collagens III, IV, and V. Activates procollagenase. Similar to stromelysin 1, but action on collagen types III, IV and V is weak. Binds 2 Zn(2+) ions per subunit. Expressed in small intestine. Weak levels in heart and lung. By wounding. The conserved cysteine present in the cysteine-switch motif binds the catalytic zinc ion, thus inhibiting the enzyme. The dissociation of the cysteine from the zinc ion upon the activation-peptide release activates the enzyme. Belongs to the peptidase M10A family.