PC3, Du145, PPC-1, C4-2, and LNCaP cells were cultured in RPMI-1640 plus 7% heat-inactivated fetal bovine serum (FBS), 100 mg/ml streptomycin, and 200 U/ml penicillin (Life Technologies). VCaP cells were cultured in DMEM supplemented with 10% FBS and antibiotics. The non-tumorigenic human prostate epithelial cell line 9 (NHP9) was maintained in serum-free PrEBM medium (Clonetics) supplemented with insulin, epidermal growth factor, hydrocortisone, bovine pituitary extract, and cholera toxin. LAPC9 and LAPC4 were xenograft tumors (21 (link),22 (link)). NOD/SCID mice were purchased from the Jackson Laboratory and breeding colonies maintained in our animal facility under standard conditions. All animal experiments were approved by Institutional Animal Care and Use Committee. Antibodies were active caspase-3 (polyclonal antibody (pAb), R&D), Ki-67 (monoclonal antibody (mAb), DAKO), BMI-1 (mAb, Cell Signaling), TGFBR1 (pAb, Abcam), EGFR (mAb, Cell Signaling), GAPDH (pAb, Santa Cruz), BrdU (mAb, Sigma), CD44 (mAb, BD Pharmingen), CD133 (mAb, Miltenyi), α2β1 (mAb, Chemicon). Isotype control antibodies and FITC- or PE-conjugated secondary antibodies were from Chemicon. Other secondary antibodies were purchased from GE Healthcare.