Fig. 7. Ablation of FRS2 in the prostatic epithelium inhibits tumorigenesis in the TRAMP prostatic tumor model. (A,B) Expression of Frs2 and Fgfr1 at the mRNA level was assessed in TRAMP prostates by in situ hybridization (A) and RT-PCR (B). Red arrows, epithelial cells; black arrows, stromal cells. Inset, wild-type control showing no expression of Fgfr1 in the epithelial compartment. T1 and T2, different, individual TRAMP tumors; C2, the C2 cell line derived from TRAMP tumors; P^WT, prostates of 6-month-old wild-type mice; P^TRAMP, prostates of 3-week-old TRAMP mice in which PIN lesions are minimal. Brain and liver were used as positive controls; β-actin as a loading control. (C) Treatment of TRAMP-C2 cells with FGF2 (10 ng/ml) for 10 minutes after serum starvation for 24 hours. Cells were lysed and the lysates analyzed by western blot with the indicated antibodies. (D) Prostate tissue sections were prepared from TRAMP mice with homozygous Frs2-null or Frs2 floxed alleles at the indicated ages and stained with Hematoxylin and Eosin (HE) or analyzed by immunohistotaining with anti-T-antigen antibody. Blue arrows, focal lesions; green arrows, normal epithelial cells. (E) PIN foci in prostates of 10-week-old TRAMP mice were identified as defined (Park et al., 2002), and the percentage area occupied by lesions quantitated. Mean±s.d. values of data from five prostates are shown. (F) Mortality of TRAMP mice with the indicated Frs2 alleles was determined from daily observation over 250 days. The percentage of mice that survived to the indicated ages is shown. pFRS2, phosphorylated FRS2; pERK1/2, phosphorylated ERK1/2; pAKT, phosphorylated AKT; F/F, homozygous TRAMP-Frs2^flox mice; CN, TRAMP-Frs2^cn mice.