To assess the mechanisms for 17a-dependent delay in posttreatment regrowth of renal cysts/cystadenomas, we performed immunohistochemical staining of p-S6 (Ser235/236) and proliferating cell nuclear antigen (PCNA), as well as TUNEL assay, in kidneys from mice withdrawn from treatments. The gene discussed is PCNA; the disease is cystic kidney disease.