Furthermore, comparing the Pde4dSMC−/− mice and the mice treated with the pan-PDE4 inhibitor rolipram, we found that rolipram elicited more profound effects on suppressing AAA than that in the Pde4dSMC−/− mice (aortic diameters, 1.425 ± 0.192 mm vs. 1.936 ± 0.203 mm). Here, PDE4A is linked to triple-A syndrome.