COX4I1 and heart failure: The COX4I1 protein, in case of myocardial insufficiency (heart failure) and dilated cardiomyopathy, is found to have decreased expression of COX4I1, which results in an impaired cytochrome c oxidase (CytOx) activity that has an important role in myocardial respiration, ultimately affecting the mitochondrial respiratory chain64,65.