Activation of Py replicon by GAL4–STAT fusion protein.

(A) Schematic diagram of GAL4–STAT fusion proteins used. (B) GAL4–STAT5A or GAL4–STAT5B was transfected with Py LTag and pPyG5OICAT, which contains a 5-tandem repeat of GAL4 binding site and Py replication origin, into BA/F3 cells. After 24 hours of culture, replication was analyzed by DpnI assay. The replicatedDpnI-resistant plasmid is indicated by the arrow. (C) The indicated doses of GAL4–STAT5 or its mutants were transfected with SRα-LTag and pPyG5OICAT into BA/F-wild cells. After 24 hours of stimulation, DpnI assay was done.