FIG. 4.

Specific binding patterns of STAT5A and STAT5B for the CIS probes. COS-7 cells transfected with expression vectors for the prolactin receptor, STAT5A, or STAT5B were treated with prolactin, and nuclear extracts were prepared (COS-STAT5A and COS-STAT5B, respectively). Bandshift assays were carried out with ³²P-labelled CIS34 probe (lanes 1 to 3 [A]), CIS12 probe (lanes 4 to 6 [A] and 1 to 9 [B]), CIS1 probe (lanes 7 and 8 [A]), or CIS2 probe (lanes 9 and 10 [A]) in the presence of different combinations of nuclear extracts (COS-STAT5A, COS-STAT5B, and UT7) as indicated by a + in the figure (++ corresponds to a double quantity of nuclear extracts).