Fig. 3.

Induction of DN R-Ras expression inhibits MPNST proliferation, migration and invasion but not survival. a Induction of DN R-Ras expression, but not expression of eGFP, reduces ³H-thymidine incorporation in the ST88-14, STS-26T, and T265-2c doxycycline-inducible stable cell lines relative to uninduced controls. 16 replicates were performed for each condition. b Induction of DN R-Ras expression, but not eGFP expression, reduces Transwell migration in ST88-14, STS-26T, and T265-2c cells. c Immunofluorescence microscopy of phalloidin-stained ST88-14 MPNST cells grown in 3D Matrigel-matrix cultures. Left images are of ST88-14 cells stably transfected with a doxycycline-inducible eGFP expression vector and right images are the same cell line stably transfected with a doxycycline-inducible DN R-Ras vector. Upper panels are uninduced cells and lower panels are cells with expression induced by doxycycline. Scalebar = 400 µm (d) Quantification of percentage of spheroids in 3D culture with invasive phenotype, defined by circularity < .65. e Calcein AM cleavage assays in ST88-14 cells grown in the absence (left) or presence (right) of serum. Induction of eGFP and DN R-Ras expression had no statistically significant effect on the number of viable cells. For all panels, * indicates p-value < .0001 for comparison to controls