As Pdgfrα is the best known single marker for fibro/adipogenic progenitors (reviewed in Lees-Shepard and Goldhamer, 2018), and because Pdgfrα-Cre;Acvr1tnR206H/+ mice recapitulate the major pathogenic manifestations of FOP, including progressive HO at all major anatomical sites affected in FOP patients (Lees-Shepard et al., 2018a; Lees-Shepard et al., 2018b), the Pdgfrα-Cre driver was ideally suited for our studies. Here, PDGFRA is linked to fibrodysplasia ossificans progressiva.