In summary, the present study on global gene expression profiling of PAI-1 knockout and wildtype hearts and kidneys helps us to formulate a possible and robust hypothesis defining a pathway involving Ankrd1-Egr1-ECM genes that may explain the molecular basis of cardiac-selective fibrosis and lack of renal fibrosis in aged PAI-1 knockout mice. Here, SERPINE1 is linked to renal fibrosis.