Inhibition of STAT5 reporter gene activity by δSTAT5 expression.

Cells from 3 clones of Ba/F3p210ΔSTAT5 cells were transfected with the β-casein luciferase construct. Twelve hours after transfection, cells were split and maintained in either the presence or absence of doxycycline (1 μg/mL) for 24 hours. Cells were then assayed for luciferase activity, and results are expressed as the percentage of activity in unstimulated controls. Induction of ΔSTAT5 in Ba/F3p210ΔSTAT5 cells by doxycycline significantly inhibited STAT5 reporter gene activity in all clones tested. No inhibition of STAT5 activity was observed when Ba/F3p210Ctrl cells were exposed to doxycycline.