Metalloproteinases that cleave gelatin, or nondenatured collagen. Two forms of gelatinase, A and B, have been identified. Gelatinase A (MMP-2) has a molecular weight of about 72,000, and gelatinase B (MMP-9) has a molecular weight of about 92,000. Both are involved in cancer angiogenesis and metastasis and are blocked by a variety of naturally occurring and synthetic inhibitors.