Therefore, we conclude that the activation and transdifferentiation of CD34+ cells into myofibroblasts in AAA is likely controlled by PDGFRb signaling induced by PDGF ligands secreted by other aortic cells, including ECs, SMCs, and macrophages, rather than by the direct effect of Ang II on CD34+ cells. The gene discussed is CD34; the disease is triple-A syndrome.