MPS1-IN-3 is a selective and potent MPS1 inhibitor with phenotypic consequences similar to those reported for published MPS1 inhibitors such as MPS1-IN-1, MPS1-IN-2, and AZD3146. MPS1-IN-3 sensitizes glioblastoma cells to vincristine both in vitro and in murine tumor models. MPS1 may be a promising therapeutic target for high-grade glioma therapy and that MPS1 inhibition by MPS1-IN-3 efficiently sensitizes glioblastoma cells to antimitotic agents.