Fig. 4. Analysis of the kinetics of GAG turnover. HMEC-1 cells were labelled with ³H-glucosamine for 24 hours and were then washed and cultured either with or without TNF- and IFN-. The cells were harvested after 4 hours and 16 hours, the GAGs were purified and incorporated ³H was measured. Bars represent the mean relative cpm for GAG derived from 10⁵ cells. The sample at 0 hours (shaded) provides a measure of the initial level of incorporation. The white bars represent unstimulated cells and the black bars indicate cells stimulated with TNF- and IFN-. The P values above the bars indicate the significance of differences between the unstimulated and stimulated groups after 4 hours and 16 hours; the error bars show the s.e.m.