Preference of GABPα and Fli-1 binding to the proximal promoters of early versus late megakaryocytic genes by EMSA. (A) EMSA gels using nuclear extracts from primary megakaryocytes are shown. On the left, the probe is the same as in Figure 1 and on the right, the probe involves the functional Ets site in the proximal promoter region of the murine cMpl gene.30 (B) EMSA using nuclear extract from COS cells or COS cells overexpressing HA-Fli-1 are shown. Equal amounts of extracts were used in each set of gels, allowing direct comparisons of relative binding intensity. αH = anti-HA tag antibody. Supershift of the HA-Fli-1 was done either using αF alone (αIIb and PF4) or with αH (cMpl and GPIX). All gels are representative studies of at least 3 similar studies with similar outcomes.
