The cytokine macrophage migration inhibitory factor (MIF) acts as a neurotrophin in the developing inner ear of the zebrafish, Danio rerio.
Shen YC, Thompson DL, Kuah MK, Wong KL, Wu KL, Linn SA, Jewett EM, Shu-Chien AC, Barald KF. Dev Biol. 2012 Mar 1; 363(1):84-94. Epub 2011 Dec 22.