DDIT3 and myocardial infarction: Furthermore, the immunohistochemical staining of rats showed that the expression of caspase-3 and CHOP in the infarction and noninfarction areas of the left ventricle significantly increased in the eight-week MI group, which confirmed that cell apoptosis existed in the myocardial tissue, the ERS pathway played a role in HF, and the activin A–follistatin system probably participated in the myocardial cell apoptosis through the ERS pathway (Figure 3).