Experimental data suggest that heightened AR activity facilitates formation of TMPRSS2:ERG, a gene fusion present in approximately 50% of tumors of patients with prostate cancer.     ///    We undertook a nested case-control study to investigate the hypothesis that shorter CAG repeat length would be associated with prostate cancer risk defined by TMPRSS2:ERG status.     ///    Our results provide supportive evidence that androgen signaling underlies the development of prostate tumors that harbor TMPRSS2:ERG.     ///    Androgen receptor CAG repeat polymorphism and risk of TMPRSS2:ERG-positive prostate cancer..     ///    "Moreover, these results suggest that TMPRSS2:ERG may represent a unique molecular subtype of prostate cancer with an etiology distinct from TMPRSS2:ERG-negative disease.. "    ///    These data suggest that shorter CAG repeats are specifically associated with development of TMPRSS2:ERG-positive prostate cancer. 