The signal transduction from insulin to its receptors and Ras has been extensively studied, while little has been reported beyond these steps. We found that the expression of human interleukin 6 gene under the control of immediate early gene promoter of human cytomegalovirus was enhanced by insulin sitmulation in Chinese hamster ovary cells. The induction effect of insulin was not significantly affected by inhibitors or activators of conventional protein kinase C, cAMP dependent protein kinase and phosphoinositide -3 kinase, however, pre-incubation of the cells with D609, a specific inhibitors of phosphatidylcholine-specific phospholipase C completely abolished the induction effect. These results clearly demonstrate that phosphatidylcholine-specific phospholipase C is a key molecule mediating insulin-induced enhancement of hIL-6 expression from the human cytomegalovirus promoter in Chinese hamster ovary cells and strongly suggest that it plays an important role in the insulin signaling pathways.Abbreviations CHO - Chinese hamster ovary; hCMV promoter - immediate early gene promoter of human cytomegalovirus; hIL-6 - human interleukin 6; PC-PLC-phosphatidylcholine-specific phospholipase C; PI-3 kinase - phosphoinositide 3 kinase; PKA - cAMP dependent protein kinase; PKC - protein kinase C.