PON1 and chronic kidney disease: In order to better understand the functional activity of circulating PON-1 protein in the study participants, we adjusted the circulating PON lactonase activity for PON-1 protein level (i.e., circulating PON lactonase activity divided by circulating PON-1 protein level) and noted that PON-1 protein adjusted lactonase activity was increased in the CKD subjects compared to the non-CKD subjects (Figure 1C).