LacZ expression of serial 30-bp deletion mutants in megakaryocytes.

The names of the mutants indicate the nucleotides deleted from the −598/+33 wild-type GPIIb promoter. For example, Δ−538/−509 shows the data from the promoter lacking the nucleotides between −538 and −509 bp. These constructs were cotransfected to undifferentiated ES cells with a plasmid carrying the neomycin-resistant gene. After G418 selection, ES cells pooled from individual wells of 6-well plates (see text) were differentiated into megakaryocytes with OP9 stromal cells in the presence of TPO. The percentages of LacZ-expressing megakaryocytes were calculated on day 8 of differentiation induction using double staining with AChE and X-gal. The results are shown as the relative percentage of LacZexpression compared with the value for the −598/+33 wild-type promoter. The data are shown as the mean ± standard deviation. The data marked with * show significant differences (P < .05 by t test) compared with the wild-type (−598/+33) promoter. The experiment was performed 2 or 3 times, and representative data are shown.