A tissue microarray containing a total of 77 prostate specimens was used (Supplementary Table 2). The tissue microarray was obtained from Provitro (Berlin, Germany; Cat #401 2209, Lot #146.1 P020212, 26–46). Detailed information on all cancer specimens can be found at http://www.provitro.com/fileadmin/provitro-data/TMA/4012209.pdf. Immunostaining was evaluated using a previously described scoring method (Kojima et al, 2012 (link)). Tissue microarray was immunostained with an Ultra-Vision Detection System (Thermo Scientific, Fremont, CA, USA) following the manufacturer's protocol. Primary rabbit polyclonal antibodies against WWP1 (1:200, ab43791; Abcam) were used for immunochemistry. The slides were treated with biotinylated goat antibodies (Histofine SAB-PO kit; Nichirei, Tokyo, Japan).