Elevated level of cardiac ECM remodeling in PAI-1^−/− mice. Both the mRNA level (A) and the protein level (B) of TGF-β in 12-week PAI-1^−/− hearts were significantly higher than in WT hearts. Q-RT-PCR analysis of transcripts of proteins associated with tissue remodeling and fibrosis in 12-week WT and PAI-1^−/− hearts, included MMP-2 (C), MMP-9 (D), TIMP-2 (E), and uPA (F). n ≥ 5 for each group; *P < .05.