TGFB1 and idiopathic pulmonary fibrosis: When we focused on the distribution of these changes in relation to the CpG Island distance, we found that in the normal fibroblasts most methylation changes induced by TGF-β1 occurred directly in the islands (67–80%), whereas in the IPF fibroblasts, the Island and Open sea were the best represented groups (between 33–54% and 50–34%, respectively; Fig 4B).