MUC1 and Patent ductus arteriosus: For this study, we selected Chinese hamster ovarian cell line (CHO) that is null for human MUC1 and a human PDA cell line BxPC3 that express low levels of endogenous human MUC1 and has SMAD4 independent TGF-β signaling, CHO cells have intact canonical TGF-β signaling pathway and were selected as a control cell line to investigate the effects of MUC1 on TGF-β signaling and phenotypic outcomes.