SPOP and prostate cancer: To avoid dramatic conformational changes in these truncated SPOP mutants caused by the loss of large peptide fragments, we applied two prostate cancer-associated SPOP point mutations, SPOP-Y87C (Tyr 87 replaced by Cys) and SPOP-W131G (Trp 131 replaced by Gly), which play dominant-negative roles in substrate binding and degradation21,22.