XBP1 and familial dilated cardiomyopathy: Several studies have shown that in patients with DCM, levels of UPR markers—such as BiP, ATF6, phosphorylated eukaryotic initiation factor 2α (P-eIF2α), and X-box Binding Protein 1—are significantly elevated, indicating that ERS and UPR pathways are activated in the myocardium of DCM patients (81, 111).