Binding of the NF-E2 promoter and TPO-induced platelet production by a DNA binding mutant of Scl (Δb). (A) NF-E2 promoter binding by HA-Δb. K562 cells expressing MIG-HA-Scl and MIG-HA-Δb were subjected to chromatin immunoprecipitation using antibodies against the HA epitope tag and E47. The left panel shows gel electrophoresis of the NF-E2 promoter PCR products as in Figure 6, while the right panel shows quantitation of the immunoprecipitated chromatin using real-time PCR. (B) Platelet production by an MIG-Δb reconstituted mouse in response to TPO. The left panel shows histograms depicting the percentage of GFP-expressing platelets in MIG-Δb reconstituted mice before (top) and after (bottom) treatment with 2 μg PEG-rhTPO for 5 days and analysis on day 8. The right panel shows the absolute numbers of GFP-negative (GFP^neg) and GFP-positive (GFP^pos) platelets in the same mouse, taking into account the platelet counts. Data are representative of 2 MIG-Δb reconstituted mice analyzed.