The SP/KLF transcription factor family contains over 25 members sharing a DNA-binding domain composed of three zinc fingers of the C(2)H(2) type. We previously identified the sixth member of the SP subfamily (Sp6). The 5' end of the Sp6 transcript was not cloned and was predicted bioinformatically. A mouse molar tooth cDNA was then isolated differing from the Sp6 sequence by its 5' end, and was named epiprofin. Sp6 and epiprofin are currently used as synonyms. Here, we show that the Sp6 transcript possesses a first exon distinct from the epiprofin one: the Sp6 gene thus uses two promoters, generating two transcript variants which differ in their first exon. Furthermore, we identified an Sp6 opposite strand transcript (Sp6os) and examined, by quantitative RT-PCR experiments, the presence and the abundance of these two transcripts in mouse tissues. We also mapped the mouse locus by FISH to chromosome 11D.