PDX1 and Patent ductus arteriosus: To complement analyses from patient samples, we employed the genetically engineered KrasLSLG12D/+;p53LSL-R172H/+;Pdx-1-Cre (KPC) mouse model that faithfully replicates the human disease, including the stromal response associated with PDA (5, 24), and provides an excellent tool to examine collagen organization during PDA progression.