NKRF and myocardial infarction: Increased MMP2 and MMP9 expression promotes increased CF migration.[22] Inactivation of MMP9 and MMP2 in vivo prevents cardiac rupture post‐MI in mice and alleviates collagen accumulation, left ventricular dilatation, and cardiac dysfunction.[23] Real time polymerase chain reaction (RT‐PCR) showed that NKRF mRNA levels significantly decreased after TNF‐α induction (Figure 3D).