Active Motif's PC-3 nuclear extract was prepared from cell cultures of the human prostate adenocarcinoma PC-3 cell line. The PC-3 cell line was derived from an advanced androgen-independent bone metastasis of a 64 year old Caucasian male patient with Grade IV prostatic cancer. PC-3 cells are considered the 'classical' prostate tumor cell line and are characterized by a high metastatic potential, the expression of Prostate Specific Antigen (PSA), and low acid phosphatase and testosterone-5-a reductase activity. PC-3 cells are most commonly used in research as a model of prostate cancer progression.