MAP2K7 and autosomal dominant polycystic kidney disease: In 1989, Grantham et al. reported that in human kidney ADPKD cells (but not normal kidney cells), vasopressin-induced cyclic 3′,5′-adenosine monophosphate (cAMP) stimulated chloride-driven fluid secretion, and B-Raf/Mek/extracellular signal-regulated pathway cell proliferation and dedifferentiation, implicating cAMP as an important regulator of growth in ADPKD kidney cysts (36, 37).