Legend. Protein disulfide isomerase (PDI) is upregulated in viable periinfarct myocardium (brown cells, above left) compared with remote myocardium (inset); apoptosis (red, above right) is infrequent in brown cells with PDI expression. PDI expression is associated with decreased apoptosis (below, left), biventricular enlargement (below, right), and heart failure. See page 1033.