(A) Pulmonary EC clusters were identified in the developing lungs from embryonic day (E)12.5 to postnatal day (P)7. EC cluster 3 (EC3) was detected at all time points (circled). (B) Gene ontology analysis of EC3 showed that the top markers in the EC3 cluster were classified under EC migration, regulation of Notch signaling, circulatory system development and angiogenesis. (C) Gene expression of ALK1, MGP, Hey1, Jag1, Notch1 and Notch 4 in the EC3 cluster. (D) MGP profile ordered by Oscope identified MGP as an oscillatory gene, suggesting that MGP is an important driver of repetitive cycles of growth.