PDGFRB and triple-A syndrome: To further validate the function of PDGFRs during AAA progression, we crossed Cd34‐CreERT2;R26‐tdTomato;Apoe−/− with Pdgfrafl/fl or Pdgfrbfl/fl mice to generate Cd34‐CreERT2;Pdgfrfl/fl;R26‐tdTomato;Apoe−/− mice to knockout PDGFRa or PDGFRb specifically in CD34+ cells (Figure S17A, Supporting Information) and used the Cd34‐CreERT2;R26‐tdTomato;Apoe−/− mice as control.