TMPRSS2 and prostate cancer: ETS FUSION POSITIVE TUMOURS: E26 Transformation Specific (ETS) transcription factor gene fusions are found in approximately half of prostate cancers,87 the commonest of which is fusion of the androgen‐responsive promoter Transmembrane Protease Serine 2 (TMPRSS2) with the ERG gene of the ETS family.55