SOX9 and idiopathic pulmonary fibrosis: Immunohistochemistry revealed a potentially previously unreported finding that SOX9 is predominantly localized to the nuclei of spindle-shaped cells in the distal fibrotic lesions including fibrotic foci and thickened subpleura of the lung, which are the predominant pathological features of IPF (Figure 1B and Supplemental Figure 2A).