Therapeutic proteins are protein-based drug candidates bioengineered in the lab for pharmaceutical and clinical applications. Based on their pharmacokinetics, the candidates can be divided into groups that (1) replace a defective or abnormal protein, (2) augment an existing path in vivo, (3) provide a new function or activity in vivo, (4) interfere with activities of a molecule or organism and (5) deliver encapsulated proteins or compounds including, cytotoxic drugs, radionuclide or effector proteins.