The protein encoded by this gene is a 43 aa peptide produced by early activated CD4+ T cells. The encoded protein helps regulate the differentiation of these cells into T helper 2 (Th2) cells. The solution structure of this protein is similar to that of vasoactive intestinal peptide, which plays a role in the differentiation of Th2 cells and Treg cells. [provided by RefSeq, Jun 2012]