The study objectives were to: (1) identify the maximally tolerated dose (MTD) of and describe adverse events associated with systemic delivery of rLAS-uPA; (2) determine if treatment with MTD rLAS-uPA resulted in a quantitative anti-tumor response, defined by a reduction in tumor volume as determined with brain magnetic resonance imaging (MRI) examinations; and (3) characterize the immune responses to rLAS-uPA therapy in dogs with naturally occurring intracranial tumors. This evidence concerns the gene PLAU and neoplasm.