DLL4 and persistent fetal circulation syndrome: While prior research suggested that PPHN PAECs have downregulated miR-30b-5p and JAG1, and upregulated DLL4, the study by Sati and colleagues provides stronger evidence of this link.2 Using RNA in situ hybridization, they show that miR-30b-5p is downregulated, DLL4 is increased and JAG1 is decreased in PPHN.