RAC1 and endothelial dysfunction: Results showed that sirolimus caused a marked endothelial dysfunction and a desensitization of the vasculature to the endothelium-independent vasodilator nitroglycerin; moreover, upregulated superoxide production was observed, in part by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase via stimulating of p67phox/rac1 expression and increased rac1 membrane association.