Recently, we show that ERRα can directly transactivate the TMPRSS2:ERG fusion gene to drive the expression of oncogenic transcription factor ERG in prostate cancer cells regardless of their AR expression status, and both ERRα and ERG can form a synergistic reciprocal regulatory loop to promote the malignant growth and metastasis potential of prostate cancer cells [29]. The gene discussed is ESRRA; the disease is prostate cancer.