ESRRG and breast cancer: Since the three members of the ERR family of orphan nuclear receptors Essra, Esrrb and Esrrg all recognize the same consensus sequence, we tested the contribution of each individual ERR on transcriptional activity of the Dub3 proximal promoter compared to the pS2 promoter, a widely used breast cancer marker gene shown to be regulated by ERRs, used here as a positive control (Figure 4A and 4B).