FCN1 and inflammatory bowel disease: Consistent with the findings of the PIBD single-cell transcriptome analysis, the immunostaining results showed that FCN1 expression was remarkably increased in colon biopsies from PIBD patients compared to non-IBD controls (Fig. 5A), and FCN1 was specifically colocalized with CD68+ macrophages in PIBD colon biopsies (Fig. 5B).