In T-helper 2 (Th2) cells, regulates the magnitude of NFAT-driven transcription of a specific subset of cytokine genes, including IL3, IL4, IL5 and IL13, but not IL2. Recruits PRMT1 to the IL4 promoter; this leads to enhancement of histone H4 'Arg-3'-methylation and facilitates subsequent histone acetylation at the IL4 locus, thus promotes robust cytokine expression. Down-regulates formation of poly-SUMO chains by UBE2I/UBC9. Interacts with NFATC2, TRAF1, TRAF2 and PRMT1. Interacts with UBE2I/UBC9. TRAF1 is associated with a fraction of NFATC2IP in the cytoplasm and prevents its translocation to the nucleus. Highest level detected in spleen, thymus and testis. Methylation at the N-terminus by PRMT1 modulates interaction with the NFAT complex and results in augmented cytokine production. Mutant mice are born at the expected Mendelian ratio and appear healthy and viable. No alteration in thymic T-cell populations, T-cell proliferation, or peripheral lymphocyte development. Inefficient type-2 antiparasitic immune response to the intestinal nematode Trichinella spiralis due to impaired IL4 and IL13 cytokine production by Th2 cells.