Fig. 7.
EMSA. (A) Megakaryocyte extracts [5 to 10 μg, detergent-free, before (−) or after (+) 15 minutes of TPO stimulation] were analyzed for the ability to bind the hSIE probe (shifted band = S). As indicated below the autoradiogram, STAT1- and STAT3-specific antisera as well as an irrelevant antiserum (IRREL) were tested for the ability to induce a supershift (SS). (B) Lysates derived from Ba/F3-mMPL cells and megakaryocytes (5 to 10 μg, detergent-containing) were evaluated for TPO-induced binding to the PRE probe (S). Antibodies specific for STATs 3, 5B, and 5A as well as irrelevant antiserum (IRREL) were evaluated for supershift activity (SS). In each of these experiments, the first two lanes had no added antiserum.