Enables cytokine activity. Involved in positive regulation of interleukin-5 production. Acts upstream of or within several processes, including B cell activation; regulation of cellular protein metabolic process; and regulation of receptor signaling pathway via JAK-STAT. Located in extracellular space. Is expressed in gut; liver; thymus; and thymus primordium. Human ortholog(s) of this gene implicated in asthma and respiratory syncytial virus infectious disease. Orthologous to human IL9 (interleukin 9). [provided by Alliance of Genome Resources, Apr 2022]