The significance of this finding is supported by: (a) the identification of a similar subpopulation (Cthrc1+ Fb) that was previously described in human pulmonary fibrosis and injured lungs, (b) the presence of an immunomodulatory subpopulation that is likely to be coordinating neutrophil infiltration, and (c) the unexpected detection of a subpopulation of fibrocartilage-like structures of cells that are molecularly and structurally similar to both Fb and chondrocytes. Here, CTHRC1 is linked to pulmonary fibrosis.