PROS1 and triple-A syndrome: Western blotting showed that compared with that in the control group, the expression of the contractile proteins SM-22α and α-SMA in the model group was significantly downregulated, while the extracellular matrix proteolytic enzyme MMP2, which promotes VSMC migration, was upregulated (p < 0.01; Fig. 2H, I) This findings suggest that mouse AAA is similar to human AAA and are consistent with the findings related to SMC phenotypic transition.