The recently suggested role for TIMP-2 in the activation of pro-MMP-2 (Itoh et al, 2001), combined with the different cell types involved in the expression of MMP-2 and its main inhibitor TIMP-2 in gastric carcinoma, indicate the importance of local cell–cell and molecule–molecule interactions in the activation process. The gene discussed is MMP2; the disease is gastric carcinoma.