Elucidation of the signaling events associated with HHT has confirmed the contribution of inadequate BMP9/ALK1/SMAD signaling in the formation of bAVMs, and as such, some research was done using tacrolimus, an anti-inflammatory FDA-approved drug, to evaluate whether it could potentiate the activity of the impaired BMP9/ALK1/SMAD pathway present in HHT patients resulting from haploinsufficiency. This evidence concerns the gene ACVRL1 and hereditary hemorrhagic telangiectasia.