E2A-hepatic leukemia factor (HLF), a chimeric transcription factor created by the t(17;19), consists of the amino terminal portion of E2A proteins, including two experimentally defined transcriptional activation domains (TADs), fused to the HLF DNA binding and protein dimerization basic leucine zipper (bZIP) domain.     ///    "To understand the mechanisms by which E2A-HLF induces leukemia and the crucial functions contributed by each constituent of the chimera, it is essential to define the normal transcriptional regulatory properties of HLF and related bZIP proteins. "