Figure 4.

Effect of Pak dominant negative mutations on ST88–14 human neurofibrosarcoma s.c. xenografts in nude mice. The growth rate for ST88–14 wild-type xenografts and xenografts of ST88–14 transfected with Pak1 and Pak1^L83,L86 is greater than for xenografts of ST88–14 transfected with Pak1 dominant negative mutations Pak1^R299 and Pak1^L83,L86,R299 (a). Tumor volumes are expressed as the ratio of observed tumor volume (Vo) to the initial tumor (Vi) on the first day each tumor reached 0.04 cm³, a reproducible and measurable volume. Each point represents the mean of five or more separate tumors. Representative tumor sections (hematoxylin/eosin-stained, 400X magnification) show spindle-shaped cells arranged in whorls and linear bands in wild-type ST88–14 (b), which are preserved relatively in ST88–14-Pak1 (c) and ST88–14-Pak1^L83,L86 (d) transfectants but not in Pak-dominant negative ST88–14-Pak1^R299 (e) or ST88–14-Pak1^L83,L86,R299 (f).