CTHRC1 and idiopathic pulmonary fibrosis: Our previous analysis of IPF fibroblasts demonstrated distinct clusters of alveolar and adventitial fibroblasts comparable with those defined in mice, along with the emergence of a CTHRC1+/COL1A1hi/ACTA2hi pathologic fibroblast subset similar to the one that arose in murine lungs after bleomycin injury (22).