STAT6 activation in PMBL-derived cell lines. (A) Nuclear extracts were prepared from control cells (UT7mpl treated with 10 nM TPO for 30 minutes), PMBL-derived cell lines (MedB1 and Karpas 1106), the Hodgkin-derived cell line (L428), and the Burkitt-derived cell line (Ramos), and were assayed in EMSA using the β-casein responsive element as probe. To get better resolution of the DNA-protein complex, the probe was run out of the gel. (B) Where indicated, anti-STAT6-specific antibody was added to the binding reaction. Arrows indicate STAT6-DNA complexes; arrowheads indicate STAT1 and STAT5 complexes. ^*STAT6 supershifted complexes.