Glycosaminoglycan production and apoptosis induction in HIF-1α-deficient chondrocytes. In the scrambled oligonucleotide-treated groups, the amount of glycosaminoglycan (GAG) produced by cultured chondrocytes was higher under hypoxic conditions than under normoxic conditions. Under hypoxic conditions, GAG levels decreased in chondrocytes deficient in hypoxia-inducible factor 1α (HIF-1α). Statistical differences were calculated using data from four independent experiments. aP < 0.01, control oligonucleotide hypoxia vs HIF-1α-antisense hypoxia; *P < 0.05; **P < 0.01.