WEE1 and Patent ductus arteriosus: Interestingly, despite the phenotypic differences observed in cell survival, all five PDA cell lines respond mechanistically to WEE1 inhibition (through MK-1775 treatment) as evidenced by a decrease in WEE1 protein expression and downstream phosphorylation of CDK1 (Fig. 1E), as also reported by other studies14, 43.