 The ETV6/CBFA2 (TEL/AML1) fusion gene occurs as a result of the chromosome translocation t(12;21)(p13;q22) in up to 30% of children diagnosed with B cell precursor (cd10+, cd19+) acute lymphoblastic leukemia.     ///    Functional characterization of ETV6 and ETV6/CBFA2 in the regulation of the MCSFR proximal promoter..     ///    Our results also indicate that the transactivation characteristics of ETV6/CBFA2 are a combination of positive and negative regulatory properties..     ///    "Our data show that the inhibition mediated by ETV6 and ETV6/CBFA2, in the context of the MCSFR promoter, depend on interactions with other proteins, not just CBFA2B. "    ///    We have shown that a 29-bp region of the MCSFR promoter containing the binding sites for CBFA2B and C/EBPa is sufficient for the inhibition by ETV6 and ETV6/CBFA2.     ///    "However, both ETV6 and ETV6/CBFA2 inhibit the activation of the promoter by CBFA2B(AML1B) and C/EBPa. "    ///    Deletion of the helix-loop-helix (HLH) region from the cDNAs of ETV6 and ETV6/CBFA2 decreased but did not completely abrogate the ability of either construct to inhibit promoter activation.     ///    Mutational analysis of the MCSFR promoter revealed that binding of both CBFA2B and C/EBPa to their respective sites is necessary for the inhibition by ETV6 and ETV6/CBFA2.     ///    "Neither ETV6 or ETV6/CBFA2 has any significant, detectable effect on the promoter by itself. "    ///    Using reporter gene assays we have functionally characterized both the normal ETV6 and ETV6/CBFA2 fusion proteins in the regulation of the MCSFR proximal promoter. 