ERG and prostate cancer: Our recent study shows that increased co-expression of ERRα and an oncogenic transcription factor ERG expressed by TMPRSS2:ERG fusion gene is closely associated with the Gleason scores and metastasis status in prostate cancer, and both ERRα and ERG can synergistically regulate each other at transcriptional level and form a reciprocal regulatory loop to promote the advanced growth of prostate cancer 18.