Xbp1 expression, a sarcoplasmic reticulum stress-responsive transcription factor, enhances the stress-responsive capacity of the sarcoplasmic reticulum and rescues cardiomyopathy caused by mitofusin/MARF deficiency without ameliorating cardiomyopathy caused by Opa1 deletion [149]. This evidence concerns the gene OPA1 and cardiomyopathy.