MKI67 and eosinophilic esophagitis: Furthermore, the administration of rmAreg to WT mice without IL-33 induced abnormal epithelial thickening and basal cell proliferation, elevated phospho-EGFR levels, and increased the number of Ki67-expressing basal cells (Fig. 4I–M, Supplementary Fig. 6B, C), suggesting that ILC2-derived Areg play a role in promoting basal cell proliferation through EGFR phosphorylation in EoE.