ERG and prostate cancer: Previously expression profiling has defined three subtypes of prostate cancer and among these, the subtype-2 prostate cancer cases, which often exhibit a more aggressive phenotype, have been found to harbor deletions at 8p21 (NKX3. 1) and 21q22 (resulting in TMPRSS2-ERG fusion) [13]; thus, loss of NKX3. 1 has been predicted to synergize with TMPRSS2-ERG fusion to promote prostate tumorigenesis, but this has not been validated experimentally.