['It is not fully understood whether intracellular calcium and/or reactive oxygen species (ROS) are involved in nuclear factor-kappaB (NF-kappaB) activation by proinflammatory cytokines. Silymarin exhibits anti-inflammatory and antioxidant effects but the effect of silymarin in human mesangial cells is largely unknown.', 'NF-kappaB binding activity was measured by electrophoretic mobility shift assay. Intracellular calcium was monitored by confocal microscopy using Fluo-3 and intracellular ROS production was determined by flow cytometry. Monocyte chemoattractant protein-1 (MCP-1) expression was measured by Northern blot analysis and ELISA.', 'NF-kappaB was activated within 30 min by tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta). Intracellular ROS was not produced until 30 min and also antioxidants such as N-acetylcysteine and tiron had no effect on the TNF-alpha- or IL-1beta-induced NF-kappaB activation. Intracellular calcium was increased by TNF-alpha and IL-1beta. Furthermore, a calcium chelator, BAPTA-AM, attenuated the NF-kappaB activation. Silymarin dose-dependently inhibited the TNF-alpha- or IL-1beta-induced NF-kappaB activation and MCP-1 expression. Silymarin also inhibited TNF-alpha-induced intracellular calcium.'] Is proinflammatory cytokine-induced NF-kappaB activation in human mesangial cells mediated through intracellular calcium but not ROS : effects of silymarin?