Nussenzweig returned to The Rockefeller University as an assistant professor in 1990 .
Nussenzweig became an associate professor in 1994 , and a professor and senior physician in 1996 .
Nussenzweig returned to The Rockefeller University as an assistant professor in 1990 and he became an associate professor in 1994 , and a professor and senior physician in 1996 .