TMPRSS2 and cancer: SFRP4 up-regulation was strongly linked to TMPRSS2:ERG rearrangement and ERG expression: Strong SFRP4 positivity increased from 5.6% and 6.3% (by IHC and FISH) in ERG negative cancers to 11.2% and 11.7% in ERG positive cancers (p < 0.0001 each, Fig. 3).