Effects of G-CSF on CXCR4 promoter activity. (A) Time course of luciferase activity after transfection of 32Dcl3 cells with the CXCR4-promoter reporter plasmid or with the control basic (empty) vector. Cells were cotransfected with Renilla luciferase reference control plasmid to account for variation in transfection efficiencies. The results are expressed as fold activation relative to basic vector after correction for Renilla luciferase activity. The representative (n = 3) results reflect the means of triplicate determinations; the error bars represent SD of the mean. (B) Effects of G-CSF preculture on the luciferase activity induced by CXCR4-promoter reporter plasmid. 32Dcl3 cells were cultured (4-72 hours) with IL-3 alone or with IL-3 plus G-CSF and then transfected with the CXCR4-promoter reporter plasmid or with the basic vector. The results are expressed as the percentage of activation of luciferase activity relative to basic vector after correction for transfection efficiencies as measured by cotransfection with Renilla luciferase control plasmid. Luciferase activation in cells cultured with IL-3 alone was set at 100%. The results reflect the means of 5 experiments; the error bars represent SD of the mean (*P < .05; **P < .02). (C) Luciferase activity after transfection with full-length CXCR4-promoter reporter plasmid and deletion mutants. The results are expressed as the percentage of activation of luciferase activity in 32Dcl3 cells precultured with IL-3 plus G-CSF relative to luciferase activity in cells precultured with IL-3 alone (set at 100%). The results reflect the means of 3 experiments; the error bars represent SD of the mean (*P < .05).