MFN2 and cardiomyopathy: In flies, Marf deficiency induces cardiomyopathy associated to sarcoplasmic reticulum stress and mitochondrial fragmentation; interestingly, however, cardiac-specific expression of Xbp1, a transcription factor that activates genes important for protein folding and ER-stress rescue, does not recover the fragmented mitochondrial morphology but fully normalized the contractile performance of Marf-deficient hearts123.