- Regulation of cytokine production in the human thymus: epidermal growth factor and transforming growth factor alpha regulate mRNA levels of interleukin 1 alpha (IL-1 alpha), IL-1 beta, and IL-6 in human thymic epithelial cells at a post-transcriptional level. Le, P.T., Lazorick, S., Whichard, L.P., Haynes, B.F., Singer, K.H. J. Exp. Med. (1991)