The non-coding RNAs are new players in cellular and molecular biology. Indeed, quantitative and functional non-coding RNA has long been underestimated. There is a great diversity and it seems that much of the genome is transcribed into RNA, while only 1.2% of DNA information is translated into proteins. Non-coding RNA has been categorized according to different specifications so large non-coding RNA includes RNA with 300 to more than 10,000 bp. In this study, we propose a new non-coding RNA named B2 discovered by differential display. B2 is a nuclear RNA which is 51,011 bp long with no significant open reading frame. This RNA has a continuous homology with the genomic DNA of the HEF1/ NEDD9/Cas-L gene located on 6p24-p25. This homology has enabled us to characterize its structure by choosing overlapping fragments to perform several RT-PCRs. B2 RNA extends from 10 kb upstream of exon 1 of the HEF1 gene on the 5' end to exon 4 HEF1 on the 3' end. In addition, a strategic choice of PCR primers enabled us to determine the location of B2 in the subcellular compartment and then real-time PCR revealed overexpression of B2 and HEF1 in certain tissues such as thymus, cervix, liver, and spleen (among the 20 tissues analysed). B2 seems especially interesting in that it can regulate apoptosis and cell proliferation by modulating HEF1. In addition, the fact that cytostatic treatments can induce B2 reinforces the interest in this new potential target in the development of anticancer treatments. These results show that this novel non-coding RNA is an attractive target.