MTOR and cystic kidney disease: In addition, ciliary dysfunction, non-antagonistic proliferation of renal tubular cells, impaired polarity of polarized and planar cells, disorder of intracellular Ca2+ levels, and abnormalities of cyclic adenosine monophosphate (cAMP), the mammalian target of rapamycin (mTOR), and other signaling pathways contribute to the formation and enlargement of renal cysts (6).