SLC9A3 and cyst: Interestingly, total and phosphorylated renal NHE3 was elevated in cystic male Ift88 KO mice; the cause of this was not examined, however, one possibility is intrarenal renin‐angiotensin system activation due to cyst compression of the renal vasculature leading to angiotensin II‐augmented NHE3 expression (Chapman, 2007).