In cystatin C transfected B16 melanoma cells, the overexpression of inhibitor resulted in the inhibition of melanoma cell mobility and of the ability to penetrate artificial matrices by about 50% (Sexton and Cox, 1997), as well as in the suppression of metastasis by at least 90%, compared to controls (Cox et al, 1999). The gene discussed is CST3; the disease is melanoma.