PROJECT DESCRIPTION The ability of glioblastomas to proliferate in an uncontrollable manner and disperse widely within normal brain define the malignant phenotype and make this disease uniformly lethal. Effectively treating glioblastoma therefore requires finding targets that drive these two components of the malignant phenotype. We have identified one such target—the myosin II family of molecular motors. We show that myosin II family members can be targeted with a non-toxic small molecule inhibitor that is CNS permeant, and that this drug suppresses tumor progression and significantly prolongs survival in murine models of glioblastoma. However, we also find that targeting myosin II family members leads to a compensatory upregulation of a variety of proliferation- stimulating signaling pathways, and that inhibiting these pathways is synthetically lethal when myosin II function is blocked. In this proposal, we will develop strategies to enhance the efficacy of a myosin II targeting strategy in treating glioblastoma that build on our novel findings. Results from these translational studies will be vital to our ongoing efforts to develop effective treatment approaches that block both glioblastoma invasion and proliferation.