TTK and cancer: The levels of Mps1 and TTK are elevated in human malignancies and it has emerged as a novel and druggable target in cancer.25 Kusakabe and co-workers identified and synthesized a selective Mps1 inhibitor 17 with outstanding anticancer potency starting from a high throughput screening hit containing an imidazo[1,2-a]pyrazine ring (Fig. 6).26 The structure-based design of molecules from the HTS hit produced several other Mps1 inhibitors along with compound 17.