A vector-based plasmid construct for suppression of AR expression in LNCaP cells. (A) Two single-stranded oligonucleotides were synthesized consisting of a 19 nucleotide of -25 to -7 bp 5'-UTR of the AR mRNA separated by a short loop sequence from the reverse complement of the same sequence. The sense strand of synthesized oligonucleatides was ended with five thymidines as termination signal. The annealed ds DNA contained Bgl II and Sfi I restriction at its 5' and 3' end of the oligonucleotides, respectively. (B) Schematic drawing of the pSiAR-EGFP vector. The expression construct was designed to expression AR siRNA driven by U6 promoter for suppression of endogenous AR expression in mammalian cells. The expression construct also contained EGFP driven by the CMV promoter constitutive expression of GFP in target cells.