Some interleukin 6 (IL-60 transcription control factors were resported as the regulator of IL-6 expression. A nuclear protein bound to interleukin 1 (IL-1) responsive element in the IL-6 promoter region was named NF-IL6 (nuclear factor for IL-6). This NF-IL6 was known to be very imporant as a transcription factor for various immuno-protein as well as for IL-6. The human NF-IL6 genes were transfected into the mouse L cells under the metallothionein promoter (MT promoter) to establish a model system for the expression of foreign gene in the mammalian cell line.