USP8 and cancer: 9-Oxo-9H-indeno[1,2-b]pyrazine-2,3-dicarbonitrile and analogs: 9-Oxo-9H-indeno[1,2-b]pyrazine-2,3-dicarbonitrile and its analogs have been identified by high-throughput screens as selective USP8 inhibitors that show anti-proliferative and pro-apoptotic activities in various cancer cell lines [213,214].