Figure 1. Isolation of aptamers that bind to murine 4-1BB.

(A) Binding of the starting RNA library and round 12 RNA pool to 4-1BB–Fc using the filter binding assay as described in Methods. (B) Sequence of random regions of clones isolated from round 12 pool. Bold text denotes identical or closely related sequences. ^#Tested for binding to 4-1BB–Fc. *The final base of the random regions of these clones was variable. ^1,2Binding was measured as a mixture of each pair.