Mark R. Frey is a Professor at the Keck School of Medicine of the University of Southern California, specializing in Pediatrics and Cancer Biology. He serves as the Admissions Chair for PIBBS, Associate Director of the PhD Program in Biomedical Biological Sciences, and is a member of the Faculty Appointments Promotion Tenure Committee. His research primarily focuses on the role of ErbB receptor tyrosine kinases in intestinal homeostasis and health, particularly through the investigation of neuregulin receptors ErbB4 and ErbB3. Frey's work highlights the importance of these receptors in maintaining intestinal epithelial barrier integrity during injury and inflammation. He has demonstrated the up-regulation of ErbB4 in response to injury, which is crucial for the survival of colon epithelial cells in the presence of TNF. His research explores the complexities of ErbB receptor signaling as both a therapeutic target in intestinal inflammation and its dual role in colorectal cancer. Frey has contributed significantly to the understanding of the function of ErbB4 in various models of inflammatory bowel disease and cancer, making him a leading expert in this field.