sentences:  The covalent attachment of PEG to a drug or therapeutic protein can "mask" the agent from the host's immune system (reducing immunogenicity and antigenicity), and increase its hydrodynamic size (size in solution), which prolongs its circulatory time by reducing renal clearance.PEGylation can also provide water solubility to hydrophobic drugs and proteins.Having proven its pharmacological advantages and acceptability, PEGylation technology is the foundation of a growing multibillion-dollar industry.