Evaluation of AGR2-aMB AGR2-aMB (40 nM) was annealed by heating to 95uC for 5 minutes in 200 mL Tris-HCl buffer (25 mM Tris-HCl, 120 mM NaCl, 0.5 mM KCl, 2 mM MgCl 2 at pH 7.4), and then rapidly cooled on ice for 10 min, and subsequently waiting for another 10 min at room temperature before use. To the solution of AGR2-aMB, various concentrations of AGR2 were added and the resulting solutions were allowed to incubate at 37uC for 30 min. To the mixture, 1 mL of streptavidin beads (about 5610 4 beads) were added and the mixture was allowed to set for 45 min in dark. After washing twice with Tris-HCl buffer, SA beads were filtered to eliminate unbound AGR2-aMB and resuspended in Tris-HCl buffer solution 250 mL before flow cytometry analysis. In selectivity tests, BSA (Tagene Biotechnology Xiamen), trypsin (Dingguo Beijing), thrombin (alfa) and IgG (Dingguo Beijing) were used. Figure S1 The sequences of 62 clones. One subfamily is guanosine-rich sequences (22 clones) , and the other is thymine-rich sequences (40 clones). (TIF) Figure S2 The dissociation constant measurement of C14A, C14B, C14C and C14D against AGR2 GST and GSH. (TIF) Figure S3 Flow cytometry assay to monitor the binding of C14B1 and its five truncated sequences with a) AGR2 (target protein) and b) GST (control protein). (TIF) Figure S4 UV thermal-denaturation experiment of C14B1. Denaturation profiles obtained at 295 nm for the aptamer at three different concentrations (2 mM, 4 mM, 8 mM). The T m (59uC) at 295 nm is independent of oligonucleotide concentration, indicating that the aptamer forms an intramolecular G-quartet. (TIF) Figure S5 The secondary structure of AGR-aMB. Stable hairpin structure is formed by intramolecular hybridization between the SA aptamer sequence and the complementary sequence of C14B 1 .