[1] He served as Vice President of Cancer Immunology at Genentech in South San Francisco, California.
While in college he maintained an interest in music but focused on the rapidly expanding field of cell biology.
Working with David Miller, he began to study Chlamydomonas and found that a significant amount of the cell wall consisted of extensin.
He became interested in endocytosis and did a postdoc with Ralph Steinman and Zanvil A. Cohn at Rockefeller University and started characterizing endosomes.
In August 2024, Roche/Genentech announced the decision to shut down its cancer immunology research department leading to the departure Mellman who has been with the company for 17 years and led the unit.