At the level of ligands and their sources these pathway level changes encompassed decreased BMP5 and increased FGF2 and SEMA3C in AF-c3’s relative to AF-c1/2 (Fig. S4E), and a gain in BMP2 from CFTR+ AT2s relative to FMO5+ AT2s (Fig. S4F). Here, BMP2 is linked to atrial fibrillation.