Thalidomide-PEG4-NH2 hydrochloride is widely used in the development of PROTACs (Proteolysis Targeting Chimeras), a cutting-edge technology in drug discovery. It serves as a key component to target specific proteins for degradation by the ubiquitin-proteasome system. This compound is particularly valuable in cancer research, where it helps degrade oncogenic proteins that are otherwise difficult to target with traditional inhibitors. Its PEG4 linker enhances solubility and stability, while the amino group allows for further conjugation with other molecules, making it versatile for designing complex therapeutic agents. Additionally, it is utilized in immunology studies to modulate protein levels involved in immune responses, offering potential in treating autoimmune diseases and inflammation.