[6] Proteins of the matrix metalloproteinase (MMP) family are involved in the breakdown of extracellular matrix in normal physiological processes, such as embryonic development, reproduction, angiogenesis, bone development, wound healing, cell migration, learning and memory, as well as in pathological processes, such as asthma, arthritis, intracerebral hemorrhage,[7] and metastasis.

The enzyme encoded by this gene degrades type IV and V collagens and other extracellular matrix proteins.

[5] Thrombospondins, intervertebral disc proteins, regulate interaction with matrix metalloproteinases (MMPs) 2 and 9, which are key effectors of ECM remodeling.

[11] MMP9 plays several important functions within neutrophil action, such as degrading extracellular matrix, activation of IL-1β, and cleavage of several chemokines.

[15] Lastly, there is significant evidence that Gelatinase B is required for the recruitment of endothelial stem cells, a critical component of angiogenesis [16] MMP9 is greatly upregulated during human respiratory epithelial healing.

[19] MMP9 is synthesized as preproenzyme of 707 amino-acid residues, including a 19 amino acid signal peptide and secreted as an inactive pro-MMP.

MMP9 has been found to be associated with numerous pathological processes, including cancer, placental malaria, immunologic and cardiovascular diseases.

[25] One of MMP9's most widely associated pathologies is the relationship to cancer, due to its role in extracellular matrix remodeling and angiogenesis.

[26] Gelatinase B plays a central role in tumor progression, from angiogenesis, to stromal remodeling, and ultimately metastasis.

However, Gelatinase B has been investigated in tumor metastasis diagnosis- Complexes of Gelatinase B/Tissue Inhibitors of Metalloproteinases are seen to be increased in gastrointestinal cancer and gynecologic malignancies [28] MMPs such as MMP9 can be involved in the development of several human malignancies, as degradation of collagen IV in basement membrane and extracellular matrix facilitates tumor progression, including invasion, metastasis, growth and angiogenesis.