RARA and Cowden disease: To catalogue RA/RAR-dependent genes in CD cells in vitro, we first looked at mIMCD-3 cells, a well-characterised CD cell line derived from the mouse inner medulla23,24, which has been widely used in studying ion channel signalling25,26, signalling during osmotic and hypertonic stress27, urea signalling28 and branching morphogenesis29 of CD cells.