SMAD4 and Patent ductus arteriosus: Besides the critical alterations induced by ITGAV in TGF-β signaling for SMAD4 intact PDA (represented by PaCa 5061 in this study), the xenograft model with the SMAD4 dysfunctional BxPC3 cells demonstrates that there are also TGF-β independent effects of ITGAV in PDA.