Enables cytokine activity. Involved in several processes, including innate immune response in mucosa; negative regulation of white fat cell proliferation; and regulation of gene expression. Acts upstream of or within several processes, including T-helper cell differentiation; positive regulation of macromolecule metabolic process; and regulation of leukocyte activation. Located in external side of plasma membrane and extracellular space. Is expressed in several structures, including brain; colon; hemolymphoid system; liver; and placenta. Used to study Sjogren's syndrome; atopic dermatitis; and type 1 diabetes mellitus. Human ortholog(s) of this gene implicated in several diseases, including asthma (multiple); autoimmune disease (multiple); hepatitis B; hepatitis C; and pancreatic cancer (multiple). Orthologous to human IL4 (interleukin 4). [provided by Alliance of Genome Resources, Apr 2022]