Insulin-like growth factor-1 (IGF-1) expression increases with the progression of cystic lesions in ADPKD and murine PKD, thus the increased expression of IGF-1 may contribute to the progression of cystic lesions. p70S6 kinase (p70S6K) is an important downstream signaling molecule of IGF-1 and is implicated in the regulation of cell cycle progression and cell proliferation.