BMP4 and triple-A syndrome: As shown in Figure 4A, genes involved in extracellular matrix functions (e.g., Col4a3–Itga1 and Fn1–Itga8), BMP signaling (Bmp4–Bmpr2 and Bmp4–Bmpr1b), and FGF signaling (Fgf2–Sdc2) were among the ligands upregulated in TAA SMCs relative to AAA SMCs.