PKD1 and cystic kidney disease: We found that PKD1 renal cysts displayed a rich network of upregulated signaling pathways for mitogenic responses, including receptor tyrosine kinases (e.g., IGF/IGF1R, FGF/FGFR, EGF/EGFR, VEGF/VEGFR), G-protein-coupled receptors, and intracellular cascades involved in calcium, cAMP and mTORC1 signaling [54].