JUNB and myocardial infarction: In patients with myocardial infarction, the expression of AP‐1 and matrix metalloproteinases (MMP) is significantly increased, indicating that AP‐1 may be crucial in ventricular remodeling.[29] AP‐1 regulates the transcription of MMP‐2 in cardiomyocytes, hence facilitating myocardial fibrosis and remodeling.