The structures of aptamers, DNA and RNA constructs, and nucleotides are shown. Indicated compounds used in this study are1 (A-E) chemically synthesized by a commercial supplier (PURIMEX, Grebenstein, Germany),2 (A) enzymatically transcribed in vitro from oligonucleotide templates using T7 RNA polymerase,3 (B and C) chemically synthesized in house using the phosphoramidite method (Gene Assembler Special, Pharmacia Biotech, Freiburg, Germany),4 (F) isolated from mouse vascular smooth muscle cells using an extraction kit (Sigma, Munich, Germany) or the DNAzol reagent (Invitrogen, Groningen, The Netherlands),5 or (F) purchased from Fermentas (St. Leon-Rot, Germany).