TMPRSS2 and Familial prostate cancer: In aggressive versions of prostate cancer, TMPRSS2 undergoes autocatalytic proteolysis at Arg255‐Ile256 (Afar et al., 2001), where the two chains may remain in combination due to interchain disulphide bridges (Chen et al., 2010) or the catalytic moiety may be secreted (Chen et al., 2010).