Commentary Kierstin L. Webster1 and Lev Becker1,2⇑ 1Committee on Molecular Metabolism and Nutrition, The University of Chicago, Chicago, IL 2Ben May Department for Cancer Research, The University of Chicago, Chicago, IL Corresponding author: Lev Becker, levb{at}uchicago.edu Triggering receptor expressed on myeloid cells 2 (TREM2) is highly expressed by innate immune cells and has been implicated in a variety of diseases, including Alzheimer disease, cancer, and diabetes.