1. Department of Chemistry and Biochemistry, and the Biodesign Institute, Arizona State University, Tempe, Arizona 85287, Department of Cancer Biology, Dana-Farber Cancer Institute, and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, Wyss Institute for Biologically Inspired Engineering at Harvard, Cambridge, Massachusetts 02138, and National Resource for Automated Molecular Microscopy, The Scripps Research Institute, La Jolla, California 92037