5Y, SHEP, and SK-N-AS cells selected for stable expression of TβRIII, TβRIII-ΔGAG, empty vector control (EV), shRNA to TβRIII (shTβRIII), or nontargeted shRNA control (shNTC). (A) Proliferation index from 3 replicates (mean ± SEM) of thymidine incorporation, normalized to empty vector or nontargeted shRNA control lines. P < 0.01 (ANOVA); *P < 0.05 (1-sample t test and 2-tailed Student’s t test). (B) Western blot for p21 in stable cell lines, with or without FGF2 treatment (1 ng/ml for 5Y, 10 ng/ml for SHEP). Densitometry for p21 normalized to β-actin is shown as percent control. (C) 5Y stable orthotopic xenografts (13 mice per group). Tumor weights (mean ± SEM) and images (scale bar in cm) after 7 weeks of growth. Different symbol colors represent different cohorts. P < 0.0001 (1-way ANOVA); pairwise comparisons P < 0.0001 EV vs. TβRIII, P < 0.05 EV vs. TβRIII-ΔGAG (Mann-Whitney) Western blots of tumor lysates. Average NF160 densitometry from 3 replicates normalized to β-actin is shown as percent control. **P < 0.01 (1-sample t test). H&E staining of tumors from each group. T, tumor; A, host adrenal cells. Scale bar: 50 μM. (D) SK-N-AS stable orthotopic xenografts. Tumor images after 4 weeks of growth (scale bar in cm). Western blot of tumor lysates for differentiation markers. (E) Tumor weights at 4 weeks (mean ± SEM). Different symbol colors represent different cohorts. *P < 0.05 (Mann-Whitney). (F) Kaplan-Meier survival analysis (10 mice per group). (G) H&E-stained contralateral adrenal glands from mice at 4 weeks (scale bar: 50 μM). Photograph of macroscopic metastasis to the contralateral adrenal gland at the 4-week end point (scale bar in cm).