APOE and hyperuricemia: Furthermore, the induction of hyperuricemia alone enhanced the abundance of MMP-9, URAT1, and p-ERK1/2 expression in the abdominal aorta in ApoE-KO mice compared with control mice (2.37-fold, n = 6, P < 0.05; 1.92-fold, n = 6, P < 0.05; and 2.51-fold, n = 6, P < 0.05).