CXCL12 and idiopathic pulmonary fibrosis: In IPF, there was an increase in the proportion of CXCR4+ cells that were of epithelial-origin (effect size 1.853, p = 0.007) (Fig. 4e) or were “activated” as they also expressed CXCL12 (effect size 1.349, p = 0.049) (Fig. 4f).