- Expression of mRNA encoding neurotrophins and neurotrophin receptors in rat thymus, spleen tissue and immunocompetent cells. Regulation of neurotrophin-4 mRNA expression by mitogens and leukotriene B4. Laurenzi, M.A., Barbany, G., Timmusk, T., Lindgren, J.A., Persson, H. Eur. J. Biochem. (1994)