CXCL12 and idiopathic pulmonary fibrosis: Using independent single-cell RNA sequencing data, we confirmed expression of CXCR4 in lymphocytes and myeloid cells (Figures S5A–S5C), while CXCL12 was expressed by mesenchymal cells (Figures S5D–S5F), consistent with a recent report identifying an increase in CD45+CXCR4+ cells within IPF tissue with strong CXCL12 expression within fibroblast foci (Jaffar et al., 2020).