Additionally, cancer cells have lesser capability to colonize the lungs of MMP2 or MMP9 deficient mice compared to wild type mice (Itoh et al., 1998, 1999) and cancer cell proliferation is decreased in tumors obtained from MMP9 knock-out mice (Bergers et al., 2000; Coussens et al., 2000). The gene discussed is MMP2; the disease is cancer.