Structures
of 1a, 2v, and 5d, and the
effects of new analogues on STAT3 DNA-binding activity in
vitro. (A) Analogues 1a, 2v, and 5d; (B–G) EMSA analysis of STAT3 DNA-binding
activity in nuclear extracts of equal total protein prepared from
v-Src-transformed fibroblasts containing activated STAT3 preincubated
with 0–100 μM of the indicated compounds for 30 min prior
to incubation with the radiolabeled hSIE probe that binds STAT3. Positions
of STAT3:DNA complexes in gel are labeled; control lanes (0) represent
nuclear extracts pretreated with 0.05% DMSO. Data are representative
of 2–3 independent determinations.