CRBN and hepatocellular carcinoma: As shown in Figure 4G, 008 triggered robust degradation of FER as well as AAK1 and GAK1 in the liver carcinoma cell line Bel7404; however, CRISPR–Cas9-meditated E3 ligase CRBN knockout significantly blocked turnover of these kinase proteins, indicating that the E3 ligase CRBN is required for PROTAC compound–mediated kinase degradation.