GGPS1 and cystic kidney disease: The tagging SNPs located in GGPS1 promoter were identified and the effect of the rs3806394 locus variant on GGPS1 promoter activity was assessed.<h4>Results</h4>Immunohistochemistry and Western blot analysis revealed that GGPPS expression was downregulated in SRC tissues and that the larger the renal cyst volume was, the lower the expression of GGPPS in the cyst lining epithelial.