To determine the effects of steviol and derivatives (isosteviol, dihydroisosteviol and 16-oxime isosteviol) on cyst formation in an in vitro model of PKD, MDCK cells seeded in collagen gel were exposed to 100 μM steviol, its 3 derivatives and 10 μM CFTRinh-172 (a CFTR inhibitor) [28] in the presence of 10 μM forskolin-containing media. The gene discussed is CFTR; the disease is cyst.