It is expressed during coexpression of Oct3/4, c-Myc, Klf4, and SOX2, four genes identified to be important in embryonic stem cell self-renewal and differentiation repression.

[8] In mice having a beta-galactosidase gene knocked into the Fbx15 locus, stain was detected in ES cells, early embryos (from two-cell to blastocyst stages), and testis tissue.

Reporter gene analyses demonstrated that the ES cell-specific expression required this 18-bp enhancer element located approximately 500 nucleotides upstream from the transcription initiation site.

This might be explained by the fact that Fbx15-/- embryonic stem cells display a proliferation defect - caused by the accumulation of the Fbx15 substrate KBP - generating a short-term bottleneck during the early stages of embryogenesis.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.