As part of the immune system, monoclonal antibodies have been used as highly specific pharmaceuticals with minimal side effects. antibody based drugs made using recombinant proteins have become extremely and increasingly useful for targeting certain diseases. for example an antibody based drug called embrel (amgen) has been very useful for treatment of rheumatoid arthritis. rheumatoid arthritis is

Rheumatoid arthritis is a disease that affects the joints and organs of the body, with signs of swellings, and inflammation due to the disability of the immune system causing autoimmune responses.

Explanation:

This disease is usually long-term and cause pain around the joints. Amgen has been useful for the treatment of this disease by hindering the tumor necrosis factor TNF from responding to the body cells.

substitution is the answer in this case

nucleus

would be most reasonable answer tbh