CXCR4 and idiopathic pulmonary fibrosis: Histologically, honeycomb cysts are lined with cuboidal or ciliated cells that express a variety of epithelial markers such as e-cadherin and basal cell-specific keratins, supporting the hypothesis that honeycomb cysts are derived from the distal airway [14] but further investigation into the cells of the honeycomb cyst is necessary before anti-CXCR4 therapies in IPF can be fully realised.