The structure of serotonin was given to Upjohn Drug Company where researchers focused on the role of serotonin in the bodily processes such as blood vessel constriction. In 1954, Betty Twarog discovered the distribution of serotonin in the brain. Further research illustrated how serotonin plays a major role in the central nervous system and digestive tract. The understanding of serotonin has led to a progression in our view of mental illness and allowed the development of antidepressants and other drugs for hypertension and migraines. After his work with serotonin, Rapport worked at the Sloan-Kettering Institute for Cancer Research. His contributions involved the activity and structures of lipids in relation to immunological activity. Specifically, he isolated cytolipin H from human cancer tissue in 1958. This led to a better understanding of our immune system. He also was a professor at the Albert Einstein College of Medicine. There he isolated two glysosphingolipids and studied antibodies to gangliosides. These findings were useful to further pharmacological studies relating these substances to demyelinating diseases such as amyotrophic lateral sclerosis (ALS). In 1968, Rapport returned to Columbia University as chief of pharmacology and professor of biochemistry. The next year, he became the chief of the new neuroscience division which combined the chemistry, pharmacology, and bacteriology divisions. He retired in 1986 and remained in the neurology department of the Albert Einstein College of Medicine as a visiting professor. Because of this work with serotonin, Rapport was awarded the Fulbright Scholarship in 1952 to study with Dr. Daniel Bovet, who later won a Nobel Prize for his work in pharmacology.