PDE4A and autosomal dominant polycystic kidney disease: Isoforms of the PDE4C family had previously been shown to localise to primary cilia and to associate with the PC1/PC2 complex as well as AC5/6, (Choi et al., 2011), and PDE4 inhibition had been shown to be sufficient to induce cystogenesis in MDCK cells as well as primary cells derived from ADPKD patients (Omar et al., 2019).