Interleukin-1 alpha and beta are polypeptide hormones with a broad range of biological activities. Both interleukins are recognized by a receptor that has been characterized as a member of the immunoglobin superfamily. The interleukin-1 receptor does not appear to be a tyrosine protein kinase. Moreover, the intracellular events that mediate the multiple interleukin-1 responses are poorly understood. Here we show that the JE and KC genes, first isolated and characterized as platelet-derived growth factor inducible in quiescent BALB/c-3T3 fibroblasts, are induced by femtomolar concentrations of recombinant interleukin-1 alpha (rlL-1). The response of JE and KC to IL-1 occurs at the transcriptional level. These observations suggest that an analysis of the JE and KC transcriptional response to rlL-1 may aid in identifying elements involved in interleukin-1-mediated signal transduction.