FIG. 6.

A Fli-1 activation domain in conjunction with the Fli-1 Ets domain is required to retain transcriptional synergy with GATA-1. (A) Schematic representations of Fli-1 constructs used alone or in combination with GATA-1 to activate the GPIbα-253 luciferase reporter. (B) HeLa cells were cotransfected with 800 ng of GPIbα-253 luciferase reporter and either 200 ng of pcDNA3 backbone (lane 1) or 200 ng of the indicated Fli-1 constructs (lanes 2 to 6), either without (open bars) or with (filled bars) 50 ng of GATA-1 expression plasmid. Total DNA was kept constant in each sample by addition of pcDNA3 backbone. Luciferase activity was measured as described for Fig. 5. Results represent mean increases of reporter activity ± standard deviations relative to a value of 1 for GPIbα-253 reporter activity alone (lane 1, open bar). Results shown are the means from three experiments performed in triplicate. Each experiment was performed at least three times with similar results.