ERG and prostate cancer: Genetic rearrangements that fuse an androgen‐regulated promoter area with a protein‐coding portion of an originally androgen‐unaffected gene are frequent in prostate cancer, with the fusion between transmembrane serine protease 2 (TMPRSS2) and ETS transcription factor ERG (ERG) (TMPRSS2‐ERG fusion) being the most prevalent.