SERPINE1 and endothelial dysfunction: Given the novelty and putative biological plausibility of CXCL12 in regulating endothelial function (whereas PAI-1 primarily effects platelets), we next sought to investigate whether CXCL12 concentrations were directly implicated in age-related endothelial dysfunction transduced by the circulating SASP milieu and if mitigation of elevated CXCL12 was a mechanism by which fisetin supplementation elicited its benefits on endothelial function with aging.