FGF9 and bronchopulmonary dysplasia: The PPAR signaling pathway was enriched with the genes of Rxrg, Fabp3, and Adipoq genes, and the MAPK pathway was enriched with genes of Cacng1, Cacng6, Egf, Cacna2d3, and Fgf9. We verified the expression of these genes in lung samples of BPD mice and BPD-Exon-treated BPD mice by RT-qPCR.