There was no significant difference in transcript levels of matrix metallopeptidase 9 (Mmp9), involved in remodeling the extracellular matrix and reported to be elevated post-myocardial infarct cardiac remodeling (Ertl and Frantz, 2005), though the overall levels were highest in γ-IR mice (Figure 5C). This evidence concerns the gene MMP9 and myocardial infarction.