The DBA/2FG-pcy mouse has a form of slowly progressive kidney disease that appears similar in many respects to that seen in the autosomal dominant form of human polycystic kidney disease. The aim of this study was to examine the mRNA expression of growth-related proteins in kidney obtained from DBA/2FG-pcy mice and control DBA/2 mice at 8, 16, and 30 wk of age. The mRNA levels encoding for proliferating cell nuclear antigen (PCNA), transforming growth factor (TGF)-beta, platelet-derived growth factor (PDGF)-A and PDGF-B chains, insulin-like growth factor (IGF)-I, and basic fibroblast growth factor (bFGF) were increased with the progression of cystic lesions in the kidneys of DBA/2FG-pcy mice. At 30 wk of age, mRNA levels of PCNA, TGF-beta, PDGF-A and PDGF-B chains, IGF-I, and bFGF were increased 5.4-fold, 4.8-fold, 4.4-fold, 3.8-fold, 3.7-fold, and 4.6-fold, respectively, compared with those of control DBA/2 mice. In contrast, mRNA levels for epidermal growth factor in kidney of DBA/2FG-pcy mice decreased with age as compared with those of DBA/2 mice. These results suggest that decreased epidermal growth factor mRNA expression and increased expression of PCNA, TGF-beta, PDGF-A and PDGF-B chains, IGF-I, and bFGF mRNA may contribute to the progression of cystic lesions in DBA/2FG-pcy mice.