It also interacts with numerous proteases involved in angiogenesis, including plasminogen, urokinase, matrix metalloproteinase, thrombin, cathepsin, and elastase.

[11] The N-terminal heparin-binding domain of TSP1, when isolated as a 25kDa fragment, has been shown to be a potent inducer of cell migration at high concentrations.

The amino-terminal end contains a tryptophan-rich motif that blocks fibroblast growth factor (FGF-2 or bFGF) driven angiogenesis.

[14][15] Type I repeats have also been shown to bind to heparin, fibronectin, TGF-β, and others, potentially antagonizing the effects of these molecules on ECs.

Bound protein fragments of the type I repeats have been shown to serve as attachment factors for both ECs and melanoma cells.

[17] The carboxy-terminal domain of TSP1 is believed to mediate cellular attachment and has been found to bind to another important receptor for TSP1, IAP (or CD47).

[20][21] One study conducted in mice has suggested that, by blocking TSP1 from binding to its cell surface receptor (CD47) normal tissue confers high resistance to cancer radiation therapy and assists in tumor death.

[23][24] Moreover, stimulating TSP1 via over-expressing prosaposin or treating with a small prosaposin-derived peptide potently inhibits and even induces regression of existing tumors in mice.