Effect of VP16-C/EBP-DBD chimeric proteins on the G-CSFR promoter activity. A, shown is a schematic representation of the VP16-C/EBP-DBD-ER chimeric proteins. B, expression of VP16-C/EBP-DBD-ER chimeric proteins in retrovirally transduced K562 cells is shown. Chimeric proteins were detected by Western blot with the anti-estrogen receptor α monoclonal antibody (Stressgen). Expression of GRB2 was detected by anti-GRB2 monoclonal antibody (610112, BD Transduction Laboratories). C, shown is luciferase activity of the GCSF-R promoter in 293T cells transfected with the VP16-C/EBP-DBD-ER expression plasmids and the GCSF-R-LUC reporter after treatment with 4-HT (12 h, 250 nm). The histogram shows -fold activation of luciferase activity over that in cells transfected with the MigRI empty vector after normalization for Renilla; error bars represent the S.D. of the mean of three independent experiments performed in triplicate. NS indicates that the difference in transactivation between N-VP16-C/EBPβ-DBD-ER and N-VP16-C/EBPα-DBD-ER is not significant; statistical significance was calculated using unpaired, two-tailed Student's t test.