PIP protein expression in primary breast tumors and in vivo models. (A) Immunohistochemistry (IHC) staining for PIP in ER negative (ER-) breast tumors. AR+ group: ≥20% of cells showing positive AR staining; AR- group: <20% of cells stained for AR. Percentage of cells with positive staining are demonstrated for each group. *P <0.01 is for AR+ versus AR-. Error Bars: ± 2SEM. (B) IHC staining for PIP in AR+ and AR- breast tumors. Magnification is at 60X. (C) IHC staining for PIP in xenograft tumors generated using MDA-MB-453 cell line. Control: a control tumor; FLU: a flutamide-treated tumor; PD: a PD0325901-treated tumor. Magnification is at 60X. (D) IHC for PIP in xenograft tumors. Percentage of cells positive for PIP was assessed using IHC and compared between each treatment group and control (CTL). * P <0.01 is for FLU or PD treatment versus CTL. Error Bars: ± 2SEM. AR, androgen receptor; SEM, standard error of the mean.