WEE1 and Patent ductus arteriosus: Limitations to making a connection between DDR status and MK-1775 in these cell lines and in all PDA tumors may be related to several factors intrinsic to PDA biology (i.e., other confounding molecular alterations such as PKMYT1 expression which phosphorylates and inhibits WEE1 targets such as CDK147, along with potential unknown drug transporter/metabolism deficiencies within these cell lines).