Transforming growth factor-β inhibits cystogenesis in human autosomal dominant polycystic kidney epithelial cells

► We identified inhibitory factor of cystogenesis secreted by kidney epithelial cells. ► TGFβ is secreted as a latent inhibitory factor of cystogenesis. ► TGFβ2 is the major endogenous TGFβ isoform secreted by renal epithelial cells. ► TGFβ activity possibly limits cystogenesis in ADPKD.