Accordingly, in neurofibromin-deficient glioblastoma and mouse embryonic fibroblasts (MEFs), the levels of Rac1-GTP, p-Pak1, p-LIMK1 and p-cofilin are relatively high, whereas expression of the NF1 1-1163 polypeptide leads to a significant decrease in each of these active signaling enzymes [11]. The gene discussed is NF1; the disease is glioblastoma.