Endothelial cells notch monocytes toward an alveolar macrophage fate

Mínguez-Martínez et al. (https://doi.org/10.1084/jem.20242085) identify a cooperative RBPJ-STAT5-SMAD4-RXRα-PPARγ transcriptional network that integrates DLL4, GM-CSF, and TGFβ signals to establish alveolar macrophage identity. Their findings position endothelial DLL4 as early licensing signal that enables recruited monocytes to acquire tissue-resident macrophage fate.