NFATC3 and Lymphadenopathy: NFAT4 shows a more restricted role in regulating T cell activity; however, double deficient mice for NFAT1 and NFAT4 experience lymphadenopathy, splenomegaly, and a strongly activated phenotype with a substantial increase in serum IgE and IgG1 levels, similar to single knock-out mice (37).