The use of TNT-PNA oligonucleotide conjugates offer many of the advantages of fluorescent detection such as high specificity, ease and safety of handling and high sensitivity with the additional unmatched advantages that result from being able to generate large numbers of tags with predefined masses and from being able to construct these sets of tags with stable isotopes generating chemically identical entities that will behave the same in labelling reactions and in separation steps. This means that multiplexed analyses with accurate quantification are now enabled in a user-friendly format. Future experiments will be directed towards evaluation of the TNT-PNA probes for post-PCR amplicon detection. In addition, the development of TNT-DNA oligonucleotide conjugates and evaluation of these probes as primers for multiplexed PCR amplification and subsequent detection of PCR amplicons will also be pursued. The ability to employ in-line capillary electrophoresis with immediate cleavage and detection of tags will be of particular interest as many genomics assays, such as restriction fragment length polymorphisms, satellite marker analysis and multiplexed PCR employ size separations and the ability to perform such analyses with the higher levels of multiplexing enabled by this technology will be of great advantage. Hairpin structure within the 3′UTR of DNA polymerase β mRNA acts as a post-transcriptional regulatory element and interacts with Hax-1 Aberrant expression of DNA polymerase β, a key enzyme involved in base excision repair, leads to genetic instability and carcinogenesis. Pol β expression has been previously shown to be regulated at the level of transcription, but there is also evidence of post-transcriptional regulation, since rat transcripts undergo alternative polyadenylation, and the resulting 3′UTR contain at least one regulatory element. Data presented here indicate that RNA of the short 3′UTR folds to form a strong secondary structure (hairpin). Its regulatory role was established utilizing a luciferase-based reporter system. Further studies led to the identification of a protein factor, which binds to this element—the anti-apoptotic, cytoskeleton-related protein Hax-1. The results of in vitro binding analysis indicate that the formation of the RNA–protein complex is significantly impaired by disruption of the hairpin motif. We demonstrate that Hax-1 binds to Pol β mRNA exclusively in the form of a dimer. Biochemical analysis revealed the presence of Hax-1 in mitochondria, but also in the nuclear matrix, which, along with its transcript-binding properties, suggests that Hax-1 plays a role in post-transcriptional regulation of expression of Pol β. In eukaryotic cells, DNA polymerase b (Pol b) is essential for base excision repair (BER) and involved in recombination and drug resistance (1, 2) . Pol b expression levels are important for the maintenance of genome integrity. On account of its low fidelity, the overexpression of Pol b, which has been reported in several cancer types, leads to a mutator phenotype associated with genetic instability and decreased sensitivity to anti-cancer chemotherapeutics (3) (4) (5) (6) . Conversely, cells deficient in DNA polymerase b display hypersensitvity to alkylating agent-induced apoptosis and chromosomal breakage (7) . Sugo et al. (8) have demonstrated that Pol b-deficient mice die immediately after birth, due to extensive apoptosis in the developing central and peripheral nervous systems. These data indicate that DNA polymerase b expression level is extremely important and must be tightly regulated.