SPOP and Familial prostate cancer: Moreover, two prostate cancer-associated SPOP mutants lacking the NLS sequence (SPOP-ΔNLS- F125 V and SPOP-ΔNLS- F133 L) accumulated exclusively in the cytoplasm as a punctate pattern similar to SPOP-ΔNLS, but these mutants did not co-localize with Myc–Caprin1, possibly because of an impaired interaction with Caprin1 (Additional file 1: Figure S4A).