It has been observed that MMP-2 and MMP-9, two most crucial MMPs in the lung are over-expressed in pulmonary edema (Negrini et al., 1996; Negrini et al., 1998; Passi et al., 1998), suggesting that MMPs may become a potential target for pulmonary edema treatment. This evidence concerns the gene MMP9 and pulmonary edema.