PML binds to STAT3 and inhibits its activity through B-box and carboxy-terminal domains.

(A) The structure of PML mutants. Dotted indicates RING domain; filled, B1 and B2 boxes; and hatched, coiled-coil domain. (B) In vitro binding between GST-STAT3 (107-377) and PML mutants was examined by GST pulldown assays. (C) NIH3T3 cells were transfected with 4 × APRE-Luc and the effector gene indicated. IL-6–induced fold activation is indicated. The results are shown as the means ± SDs of triplicate cultures. Similar results were obtained from at least 4 independent experiments.