Pre-B-Cell Leukemia Homeobox Protein 1 (PBX1)

Human pre-B-cell acute lymphoblastic leukemias are frequently associated with a t(1;19)(q23;p13.3) chromosomal rearrangement. Kamps et al. (1990) and Nourse et al. (1990) demonstrated that several cell lines carrying this translocation synthesize chimeric mRNAs with 5-prime sequences encoded by the E2A transcription factor gene on chromosome 19 and 3-prime sequences encoded by a homeobox-related sequence, called Prl or PBX1, on chromosome 1.

In the chimeric transcription factor, the DNA binding domain of E2A is replaced by a putative DNA binding domain of PBX1. In 3 cell lines reported by Nourse et al. (1990), identical E2A-Prl mRNA junctions were observed, suggesting that the fusion transcripts are a consistent feature of this translocation.