PML inhibits DNA binding activity of STAT3.

(A) Functional domains of STAT3 and the structure of GST-STAT3. Gray indicates coiled-coil domain; black, DNA binding domain; dotted, linker domain; and hatched, SH2 domain. (B) In vitro binding between PML and GST-STAT3 was examined by GST pulldown assays (upper panel). Coomassie brilliant blue staining of each GST-STAT3 protein (lower panel). An arrow indicates the partially degraded product. (C) 293T cells expressing STAT3 and G-CSF-R/gp130 with or without PML were cultured in the presence or absence of 30 ng/mL G-CSF for 30 minutes. Then, nuclear extracts were isolated and subjected to EMSA. An arrow indicates the DNA binding complex including STAT3. c indicates wild-type competitor; mc, mutant competitor; Ab, anti-STAT3 Ab.