PKR is involved in cartilage matrix homeostasis. To determine whether PKR mediates the observed changes in chondrocyte matrix homeostasis, PKR activity was inhibited by adding 1 mmol/l 2AP to duplicate cultures. (a) Inhibition of PKR in untreated, control cells caused an increase in cell associated collagen. (b) Addition of 2AP to sphingomyelinase-treated cultures resulted in a significant reduction in the amount of de novo sGAG and collagen in the media. Data are presented as mean ± strandard error. * P < 0.05. 2AP, 2-aminopurine; cpm, counts/min; PKR, protein kinase R; sGAG, sulphated glycosaminoglycan.
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