This study also found a positive correlation between bile duct p21 expression and bile duct loss in biliary atresia patients, insinuating that the NCAM-positive DR cells (suspected to be HPCs) could be attempting to resolve bile duct loss in biliary atresia patients by differentiating into bile duct epithelial cells (Sasaki et al., 2018b). The gene discussed is NCAM1; the disease is biliary atresia.