SCO2 and triple-A syndrome: Notably, knockout of p53 promoted Ang II-induced AAA via inhibiting the expression of cytochrome C oxidase assembly protein 2 (SCO2) which is a component of the complex IV.40 Accordingly, the enzymatic activities of citrate synthase and cytochrome C oxidase, serving as biomarkers of mitochondrial respiratory chain functionality, were significantly reduced in the AAA aorta146.