Furthermore, we have successfully used this anti-CD4 immunoPET tracer to detect T cell repopulation in a model of hematopoietic stem cell transplantation [11] and to identify CD4+ T cells in the colon, ceca, and mesenteric lymph nodes of mice with DSS-induced colitis (a mouse model of inflammatory bowel disease) [15]. The gene discussed is CD4; the disease is inflammatory bowel disease.