Deletion of polycystin-1 increased cAMP and switched tubule formation by principal-like MDCK cells to cyst formation, and pharmacological elevation of cAMP in polycystin-1-competent cells caused cyst formation, impaired plasticity, nondirectional migration, and mis-orientation strongly resembling the phenotype of polycystin-1-deficient cells (Scholz et al., 2022). This evidence concerns the gene PKD1 and cyst.