Disclosed are compositions and methods useful in the reduction of p11 protein activity in cancer cells. P11 protein is demonstrated to affect plasmin production and activity, MMP activity, plasminogen activation, antiangiogenic plasmin fragment production, cell invasion, tumor development and metastasis. Compositions that modulate levels of p11 either up or down are demonstrated to be effective in reducing tumor development. Also disclosed are cancer treatment methods that employ compositions that modulate p11 activity and clonal cell lines and assays useful for the identification of compositions that modulate p11 activity.
