Phthalimide-PEG4-MPDM-OH, a PROTAC linker with a PEGs composition, has applications in the synthesis of various PROTACs. These PROTACs consist of a linker connecting two distinct ligands: one binds to an E3 ubiquitin ligase, while the other binds to the target protein. By leveraging the intracellular ubiquitin-proteasome system, PROTACs selectively induce the degradation of target proteins [1].