ACVRL1 and diabetic kidney disease: Several proangiogenic factors have been identified as being upregulated in DKD, such as leucine-rich α-2-glycoprotein 1 (LRG1), which enhances TGF-β/activin receptor-like kinase 1 (ALK1)-Smad1/5/8 signaling in GECs, promoting glomerular angiogenesis [20,52].