We recently demonstrated that a TF network containing members of the HNF4, HNF1, FOXA and GATA4/6 subfamilies broadly defined the core gene regulatory pathways in BO and that this network is retained in OAC (Fig. 5E; Rogerson et al., 2019; Chen et al., 2020). This evidence concerns the gene HNF4A and bronchiolitis obliterans syndrome.