The binding of i) anti-sortilin affibodies, ii) the PGRN C-terminus, iii) A3-PGRNC fusion proteins, and iv) a negative control affibody (Zwt) to the sortilin high-expressing glioblastoma cell line U-251 and the control prostate cancer cell line PC-3 was compared. The gene discussed is SORT1; the disease is prostate cancer.