Dr. Roberts investigated the role of extracellular matrix components in the tumor microenvironment in regulating tumor angiogenesis and antitumor immunity. His group discovered that thrombospondin-1 signaling through its receptor CD47 controls vascular cell responses to ischemic stress by enhancing nitric oxide/cGMP signaling and cellular responses to genotoxic stress by induction of protective autophagy, induction of anabolic metabolism, and enhanced DNA repair. CD47 also regulates stem cell self-renewal by controlling c-Myc. His lab developed novel therapeutics targeting CD47 that improve survival of ischemic injuries and increase resistance of nonmalignant cells and tissues to genotoxic stress caused by chemotherapy and ionizing radiation. The same agents enhance ablation of tumors by radio- and chemotherapy by activating CD8 T cell and NK cell cytotoxic activities.