CXCR4 promoter activity with Gfi-1 overexpression and Gfi-1 binding to CXCR4 upstream sequences. (A) Luciferase activity after transfection of CXCR4 reporter plasmids in 32Dcl3 cells overexpressing Gfi-1. The results reflect the percentage of the mean activation of luciferase activity in 32Dcl3 cells transduced with Gfi-1 relative to luciferase activity in control-transduced cells (set at 100%). The results reflect the means of 4 experiments; the error bars represent SD of the mean (*P < .05). (B) Representative ChIP results from cell lysates of 32Dcl3 cells overexpressing Gfi-1 (Gfi-1–GFP) or control (GFP). Anti–Gfi-1 antibodies and control IgG were used for immunoprecipitation. The results reflect PCR amplification of genomic sequences upstream of the CXCR4 gene transcription start site (−1427/−1441). (C) PCR results from the indicated primer sets after ChIP of cell lysates from 32Dcl3 cells transduced with Gfi-1; representative results. (D) Cell lysates from 32Dcl3 cells cultured for 3 days with IL-3 alone or with IL-3 plus G-CSF were used for ChIP with antibodies to Gfi-1 or control IgG. Representative PCR results from the indicated primer sets.