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]. The gene discussed is XBP1; the disease is cardiomyopathy.