Previously it was shown that synthetically generated CPP2 activate ECs in vitro.[22, 23] Additionally, serum from CKD patients upregulated expression of EC activation markers in vitro.[24] In order to assess the association between circulating CPP counts and EC activation in humans in vivo, plasma and serum of both healthy kidney donors (N = 17) and CKD patients (N = 34) was collected. The gene discussed is CPP; the disease is chronic kidney disease.