Based on the literature and patients data, Kucera et al. [131] have found that, among MMPs 1–3 and 7–9, systemic levels of MMP-1, MMP-9 and, especially, of MMP-7 can serve as diagnostic markers for gastric cancer; MMP-7 was also evaluated as the best gastric cancer predictor. The gene discussed is MMP9; the disease is gastric cancer.