 It is though important to realize that AR specificity does not necessarily translate "in vivo", since NTD antagonists may also interact with protein targets other than AR.AR activation requires the formation of a functional activation function 2 (AF2) region in AR LBD that mediates the interactions between AR and various transcription cofactors.Therefore, most of the research on NTD AR antagonists focuses on peptides that may directly block the AF2 in AR LBD from protein surface.