 It seems clear that androgen receptor (AR)-regulated expression of the TMPRSS2:ERG fusion gene plays an early role in prostate cancer (PC) development or progression, but the extent to which TMPRSS2:ERG is down-regulated in response to androgen deprivation therapy (ADT) and whether AR reactivates TMPRSS2:ERG expression in castration-resistant PC (CRPC) have not been determined.     ///    "To further assess whether TMPRSS2:ERG expression is initially down-regulated in response to ADT, we examined VCaP cells, which express the TMPRSS2:ERG fusion gene, and xenografts. "    ///    Reactivation of androgen receptor-regulated TMPRSS2:ERG gene expression in castration-resistant prostate cancer..     ///    "These results show that expression of TMPRSS2:ERG, similarly to other AR-regulated genes, is restored in CRPC and may contribute to tumor progression.. "    ///    "We show that ERG message levels in TMPRSS2:ERG fusion-positive CRPC are comparable with the levels in fusion gene-positive primary PC, consistent with the conclusion that the TMPRSS2:ERG expression is reactivated by AR in CRPC. "