1. Department of Analytical and Formulation Sciences, Amgen Inc., Seattle, Washington 98119
2. Department of Analytical and Formulation Sciences, Amgen Inc., Thousand Oaks, California 91320
3. Department of Protein Science, Amgen Inc., Thousand Oaks, California 91320
4. Department of Formulation and Analytical Resources, Amgen Inc., Thousand Oaks, California 91320