Notably, as identified in HMGB1 expression analysis, p53 expression was associated with presence of neoplastic progression even although this was not histologically present in the endoscopically sampled mucosa; patients who had progressed to dysplasia expressed stronger nuclear p53 in their background BO epithelia (50% moderate + strong intensity), compared with patients who had not progressed (9% moderate + strong intensity), p = 0.001. The gene discussed is HMGB1; the disease is bronchiolitis obliterans syndrome.