The cystic fibrosis (CF) gene encodes a cAMP-regulated chloride channel, the CF transmembrane conductance regulator (CFTR). PPQ-102 is a cell-permeable pyrimido-pyrrolo-quinoxalinedione that reversibly inhibits CFTR chloride channels with an IC50 value of 90 nM. At 0.5-5 μM, PPQ-102 has been used to reduce the size and number of renal cysts in a neonatal kidney organ culture model of polycystic kidney disease. At 1 μM, PPQ-102 can increase vascular endothelial growth factor-A production in cultured airway epithelial NCI-H292 cells, triggering epidermal growth factor receptor phosphorylation.