CREB1 and pachyonychia congenita: We observed RAR and CREB1 binding sites in that enhancer region (Supplementary Fig. 20), and these transcription factor binding motifs were enriched in accessible regions of PC lineage in ADPKD kidneys (Fig. 8i), suggesting that GPRC5A is regulated by retinoic acid signaling and cAMP signaling pathways.