HNF4A and bronchiolitis obliterans syndrome: Furthermore, highly connected GRNs centred on the core BO TF network were observed in the transitory foregut epithelial cells (Fig. S10A), including links to many well-known markers of BO (Fig. S10B), and the disease gene ontology terms ‘Barrett's oesophagus’ and ‘intestinal metaplasia’ featured prominently within individual and combined regulons for the HNF4A, FOXA3 and GATA5 TFs (Fig. 6I; Fig. S10C-E).