ERG and prostate cancer: For the purpose of this study, we compared PTPN12 expression with TMPRSS2:ERG fusion because this is the most common molecular alteration in prostate cancer [51], 12 different chromosomal deletions representing the next most common genomic alterations in prostate cancer [52], the Ki67 labeling index because of its pivotal role in cancer aggressiveness [53], and immunohistochemical HER2 expression because of the earlier well described interaction with PTPN12 [3, 54].