Tumor microenviroument is known to play a significant role in carcinoma development and progression.Cytokines produced by carcinoma cells are believed to modulate stromal cells to produce growth, angiogenic, and metastatic factors which in turn provide the tumor with the necessary mieroenviroument for expansion and invasion.Transforming growth factor beta (TGFβ) has been implicated as a candidate cytokine to mediate this communication.However, how its signaling in stromal cells regulates tumorigenesis and tumor progression remains unresolved.We have found that normal, pre-senescent prostate stromal cells cotransplanted with prostate carcinoma cells subcutaneously into nude mice reduced tumor latency and accelerated tumor growth.