To determine whether the protein expression level of ETV4AAA in the mouse anterior prostate is comparable to that in human prostate cancer, we performed ETV4 IHC using the same conditions on a patient-derived xenograft (PDX) model with TMPRSS2-ETV4 fusion (MDA PCa 175-6) and a control PDX (MDA PCa 173-2) from MD Anderson (MDA PCa program) deposited in biobank (37). Here, TMPRSS2 is linked to Familial prostate cancer.