2019-present, Arthur D. Riggs Distinguished Chair in Diabetes & Metabolism Research, City of Hope, Duarte, CA
2020-present, Chair, Department of Translational Research & Cellular Therapeutics, Associate Director, Diabetes & Metabolism Research Institute at City of Hope, Duarte, CA
2015-2020, Chair, Department of Diabetes, Endocrinology & Metabolism, City of Hope, Duarte, CA
2011-2015, Director, Division of Development & Translational Diabetes and Endocrine Research, Beckman Research Institute of City of Hope, Duarte, CA
2009-2015, Professor, Department of Diabetes and Metabolic Disease Research, Beckman Research Institute of City of Hope, Duarte, CA
2008-present, Professor, Department of Diabetes, Endocrinology & Metabolism, City of Hope, Duarte, CA
2008-2020, Chair, Department of Diabetes, Endocrinology & Metabolism, City of Hope, Duarte, CA
1996-present, Associate Clinical Professor, Division of Endocrinology, Department of Medicine, Harbor-UCLA Medical Center, Torrance, CA
1999-2010, Assistant Program Director, General Clinical Research Center, City of Hope, Duarte, CA
1999-2000, Acting Director, Department of Diabetes, Endocrinology & Metabolism, City of Hope, Duarte, CA
1996-1998, Consultant Endocrinologist, King Faisal Hospital & Research Center, Riyadh, Saudi Arabia
1991-1999, Assistant Staff Physician, Department of Diabetes, Endocrinology & Metabolism, City of Hope, Duarte, CA
1982-1984, Assistant Program Director, General Clinical Research Center, Harbor-UCLA Medical Center, Torrance, CA
1973-1975, Assistant Lecturer, Department of Biochemistry, Tanta University, Egypt