['Various tumours exhibit glycosaminoglycan rich, and in particular hyaluronan rich matrices surrounding them that facilitate tumour growth and invasion. In many tumours, this matrix is predominantly synthesized by fibroblasts following stimulation by tumour cell-derived factors.', 'To determine what effect tumour cell-conditioned medium has upon fibroblast glycosaminoglycan synthesis when cells were cultured as monolayers and within contracted collagen lattices.', 'Serum-free conditioned medium from melanoma cell lines (C8161, MV3, A375 and Hs294T) was examined for its ability to stimulate the incorporation of 3H-glucosamine and 35SO4 into glycosaminoglycans synthesized by fibroblasts.', 'Conditioned medium from all four melanoma cell lines exhibited potent glycosaminoglycan-stimulating activity. In monolayer culture, C8161-conditioned medium stimulated a 4.2-fold increase in fibroblast hyaluronan, and a 9.9-fold increase in sulphated glycosaminoglycan synthesis, while 35SO4 incorporation was increased only 2.1-fold. In collagen lattice cultures, C8161-conditioned medium stimulated a 4.9-fold increase in hyaluronan synthesis, a 5.4-fold increase in sulphated glycosaminoglycans, and a 1.3-fold increase in 35SO4 incorporation.'] Do melanoma cell-derived factors stimulate glycosaminoglycan synthesis by fibroblasts cultured as monolayers and within contracted collagen lattices?