Mendelsohn remained on the faculty as co-director of the new Sheikh Khalifa Bin Zayed Al Nahyan Institute for Personalized Cancer Therapy.

When he arrived, Mendelsohn's focus shifted from his expertise in laboratory research and clinical trials to leading an institution that employs about 18,000 people and serves 100,000 patients yearly, with a budget of more than $3.3 billion.

[3][4] When Mendelsohn joined MD Anderson, he had an international reputation for his research on how the binding of growth factors to cell-surface receptors regulates cell functions.

He and Gordon H. Sato and their collaborators in California produced monoclonal antibody 225, which inhibits human cancer cell proliferation by blocking the signaling pathways that are activated by epidermal growth factor receptors.

His subsequent research in the laboratory and clinic pioneered the universally adopted concept of anti-receptor therapy that targets key cell signaling pathways as a new form of cancer treatment.