Protein hydrolysis targeting chimeric (PROTAC) is emerging as a promising technology in the realm of drug discovery. Unlike traditional occupancy-driven drug design, it aims to degrade drug target protein through hijacking the ubiquitin proteasome system (UPS) in eukaryotic cells . A standard PROTAC molecule consists of three parts, namely, a warhead fragment that binds to the protein of interest (POI), a warhead fragment that binds to the E3 ubiquitin ligase (E3 ligand), and a linker segment that connects the two fragments. This assembly method allows the PROTAC molecule to bring ubiquitinase to the vicinity of POI to ubiquitinate the POI and the ubiquitinated POI is then degraded by the UPS. It has exhibited some unique advantages over traditional small-molecule drugs. For example, as UPS is involved in degradation of more than 80% of proteins in cells , the PROTAC technology is theoretically able to degrade most proteins in cells. Secondly, PROTAC mediated degradation process does not rely on high affinity of the warhead to POI , so there is less restriction on the binding site of POI. This greatly expands drug target space so that many traditionally undruggable proteins may become druggable via PROTAC modalities . In addition, PROTAC molecule can eliminate all functions of POI through protein degradation, rather than just blocking warhead mediated biological functions, which may lead to drug resistance caused by mutations at the binding site of POI . Since the concept of PROTAC was proposed by Crews and coworkers , the great potential of the technology has attracted huge interests among researchers from academics as well as pharmaceutical industry. Currently a few PROTAC drugs have moved into clinical stage . Some recent reviews have comprehensively summarized the characteristics of PROTACs .