Malfait AM, Verbruggen G, Veys EM, Lambert J, De Ridder L, Cornelissen M. Comparative and combined effects of interleukin 6, interleukin 1 beta, and tumor necrosis factor alpha on proteoglycan metabolism of human articular chondrocytes cultured in agarose. J Rheumatol. 1994 Feb; 21(2):314-20.