TMPRSS2 and Familial prostate cancer: In the TMPRSS2:ETV5 fusion event, exons 1 to 3 of TMPRSS2 are fused to exon 2 of ETV5. Although this rearrangement is also absent in all known prostate cancer cell lines, functional studies of ETV5 overexpression performed on the RWPE model produced very similar results to those obtained with the RWPE-ETV1 overexpression model (Helgeson et al., 2008).