Decreased TGF-β1 expression in the group treated with PFD confirms the ability of this substance to decrease the expression of this profibrogenic cytokine and transcriptionally and translationally promote the homeostatic regulation of collagen synthesis and degradation in the ECM [11, 32], as reported in experimental pulmonary [16, 27] and tracheal [24] studies. This evidence concerns the gene TGFB1 and polyostotic fibrous dysplasia.