Epithelial to mesenchymal transition, also a well-known pathogenic phenomenon in BOS, was enhanced by SERPINA3 in triple-negative breast cancer and glioblastoma.45, 46 Future analysis of SERPINA3 lung tissue expression, BAL fluid levels collected prospectively, and validation in a larger cohort in patients with BOS and non-BOS patients’ serum would aid in further elucidating the role of SERPINA3 in BOS. The gene discussed is SERPINA3; the disease is Buschke-Ollendorff syndrome.