MTDH and pachyonychia congenita: To analyze the significance of this interaction in vivo we generated mice with a conditional allele of Snd1. We find that Snd1 is necessary for the growth of PC in mice with prostate-gland specific overexpression of ERG and inactivation of Pten. Mechanistically, we find that ERG upregulation increases nuclear localization of SND1/MTDH and nuclear localized SND1 promotes PC cell transformation independently of ERG overexpression.