 inoculation of tumorigenic prostatic stroma and nontumorigenic prostatic epithelia into the subcutaneous space of syngeneic rats induced the development of carcinosarcoma . 
 the induced tumors , which were composed of a mixture of adenocarcinoma and fibrosarcoma , were androgen responsive . 
 this model offers a novel mechanism for prostatic carcinogenesis in which prostatic fibroblasts determine epithelial growth , androgen responsiveness , and tumorigenicity . 
 our results emphasize the potential importance of an epigenetic pathway in prostatic carcinogenesis.imagesfigure 1 . 
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