LRP1 and abdominal aortic aneurysm: Moreover, platelet-derived growth factor (PDGF)-BB, a stimulator of vascular smooth muscle cells (VSMC), proliferation, is found to be regulated by the endocytic regulator LRP1 (low density lipoprotein receptor-related protein 1), which is associated with abdominal aortic aneurysm (AAA) [117].