For various reasons, the project developed not exactly along the lines of the original proposal. The critical mouse line for the project, namely mice expressing human APOBEC3b conditionally upon induction, turned out to be incorrectly targeted and had to be regenerated at the MDC (work in progress). During this process, Dr. Franklin played a decisive role in the analysis of the role of a transcription factor, FOXO1, as a master regulator in the control of the germinal center reaction Dark Zone, where antigen-activated B cells undergo somatic hypermutation in response to antigen stimulation and are selected to become high-affinity antigen binding cells. He also initiated an investigation into the structure of the enzyme mediating somatic hypermutation, AID, and began to analyze the role of FOXO1 in controlling the synapsis of switch regions in mediating antibody class switch recombination. He also played a critical role in the finalization of a publication demonstrating the integration of signals through the B cell antigen receptor with Toll-like receptors controlling B cell proliferation in the B cell response to pathogens. Two publications in high-ranking journals have resulted from these efforts (Sander et al. Immunity 2015; Otipoby et al. PNAS 2015), and experimental work along the lines of the original proposal are ongoing.