Dr. Andrew Yen (ay13 at, a professor in the Department of Biomedical Sciences, is a member of several graduate fields. His undergraduate and graduate training at Haverford College (BA, physics/mathematics 1969), University of Washington (MS, physics 1970) and Cornell University (PhD, biophysics 1976) led to postdoctoral work at Harvard with A.B. Pardee and subsequent faculty appointments at the Sloan-Kettering Institute for Cancer Research, the University of Iowa, and now Cornell University. Dr. Yen’s research has focused on the cellular/molecular control mechanisms regulating cell growth and differentiation which may be pathologically aberrant in cancer. His work has been supported by the National Institutes of Health, The American Institute for Cancer Research, The Council for Tobacco Research, The Children’s Leukemia Research Foundation, The United States Department of Agriculture, and the March of Dimes Foundation. Dr. Yen is Director of Graduate Studies in Environmental Toxicology, Director of the Biomedical Sciences Flow Cytometry Core Laboratory, and Associate Director of the Institute for Comparative Environmental Toxicology.

Dr. Rodica Petruta Bunaciu (rpb78 at, a research associate. Petruta received her B.S. in Biochemistry from the  University of Bucharest in Romania.; the title of her B.S. thesis was: “The effects of some organotins on conventional animals in normal conditions and immunologic stress.” Her M.S. in Molecular Biology was also awarded from the University of Bucharest. The title of her M. S. thesis was: “The influence of the ascorbic acid on the proapoptotic and immunosuppressing effect of aflatoxin B1.” Petruta received her PhD from the Nutritional Sciences Department of the University of Kentucky, Lexington; the title of her PhD thesis was: “The Effect of Polychlorinated Biphenyls on Liver Tumor Promotion: A Role for Kupffer Cells?” Her current research focuses on the modulation of cell differentiation by the aryl hydrocarbon receptor.

Dr. Wendy Mercer Geil (wkm26 at,  a postdoctoral associate. Wendy received her undergraduate degree in chemistry from Boise State University, and her PhD in Chemistry from the California Institute of Technology. Wendy’s research focuses on the transcriptional role of the kinase Raf-1 in leukemic cells undergoing RA-induced differentiation. Prolonged MAPK signaling is a characteristic feature of RA-induced differentiation in multiple types of leukemic cells; previously thought to be a cytosolic protein, Raf-1 is transported to the nucleus 48 hr after RA treatment and provides important transcriptional regulation of CXCR5, a protein necessary for HL-60 differentiation, as well as other targets.

Robert MacDonald (rjm457 at, a graduate student. Rob received a bachelor’s degree in biochemistry and molecular biology and a master’s degree in biotechnology from Boston University and is currently a PhD student in environmental toxicology. His research is aimed at better understanding the role of CD38, an ectoenzyme receptor, in the retinoic acid-induced differentiation of HL-60 human myeloid leukemia cells. Through a better understanding of the specific signals involved in the differentiation process, targets for the development of specific drugs to induce differentiation of aberrant cells may be identified. The ultimate goal of the work is to help to demonstrate that differentiation therapy, while generally limited to the treatment of certain types of leukemia today, may be more broadly applicable, offering a milder and potentially more effective alternative to traditional radiation and chemotherapy-based cancer treatments.

Holly Jensen (haj25 at, a graduate student. Holly received her undergraduate degree in chemical engineering from Rensselaer Polytechnic Institute. Her research features collaboration between Dr. Andrew Yen and Dr. Jeffrey D. Varner (Department of Chemical and Biomolecular Engineering). Her project is focused on understanding retinoic acid-induced differentiation mechanisms and cell fate decisions in bipotent HL-60 leukemic progenitor cells. Because emergent resistance to retinoic acid (RA) therapy remains an obstacle, she developed two novel, sequentially emergent, RA-resistant HL-60 cell lines for study. We have shown that differentiation in the two RA-resistant HL-60 cells lines can be rescued with the Src-family kinase inhibitor PP2 and with vitamin D3, another differentiation induction therapy. These results have interesting implications toward lineage-specific mechanisms and overcoming resistance.


Jacqueline Watkins

Harmony Yourish

Aaron Wallace

Chris Ibabao


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