SMAD4 and Patent ductus arteriosus: As SMAD4 is part of the transforming growth factor-β (TGF-β) signaling pathway and is inactivated in 50% of PDA patients [20] – resulting in dysfunctional canonical TGF-β signaling in the corresponding tumors – we additionally included the cell line BxPC3 with SMAD4 deletion as a model cell line for this patient subset.