The CXCR4 promoter is regulated by Myb proteins. (A) Structures of c-Myb and v-Myb proteins. The diagrams depict the structures of the c-Myb and v-Myb proteins, which share conserved domains (shaded) involved in DNA binding and regulation. The oncogenic v-Myb protein is truncated at both ends and has a number of point mutations represented by white dots. The locations of the epitopes for antibodies (Abs) 1493 and 1.1 are indicated. (B) Structure of the CXCR4 gene promoter. The region upstream of the human CXCR4 gene is diagrammed, with putative Myb binding sites indicated by gray boxes. The arrow indicates the start site and direction of transcription. (C) Activation of a CXCR4 reporter gene. A reporter construct containing the CXCR4 promoter upstream of the luciferase reporter gene was co-transfected into HEK293 cells along with control plasmid (vector) or plasmids expressing c-Myb or v-Myb, as indicated. The figure shows reporter gene activity. Error bars show standard deviation of triplicate assays. (D) MCF-7 cells were transduced with a lentivirus expressing FLAG-tagged v-Myb. ChIP was performed with anti-FLAG antibodies (gray Bars) or control IgG (black bars). QPCR was performed with primers specific to CXCR4 and GAPDH. Data is normalized relative to percent of input. Error bars represent standard deviation of triplicate PCR reactions.