The Institute also offers a number of postdoc and junior professorship positions. He was a postdoc at Cornell University. It only offers Master's, PhD, and Postdoc programs. Afterwards, he joined Princeton university as a postdoc. He became a postdoc at the Max Planck Institute in Munich, studying bacteriophages. He earned his postdoc from University of California, Berkeley in 2004. As a postdoc he was at Michigan State University. He worked as a postdoc at IAS and Microsoft Research (1998-2001). He did his postdoc in mesoscopic physics at MIT. As a postdoc in the Masamune lab she worked with the enzyme beta-ketothiolase. He spent two (2) years as a postdoc at the University of Toronto. In 1965 he became a postdoc at the University of Northern Iowa. He was selected for the prestigious Cornell Tech Runway Program postdoc. As a postdoc, he began work on using TAL effectors to control gene transcription. From 1957 to 1958, MacArthur worked as a postdoc with David Lack.