Fig. 5. Activation of Mmp-9 by HA is not abolished in TLR4-deficient embryonic fibroblasts. Wild-type (WT) or TLR4-negative (TLR4^-/-) fibroblasts were treated with or without rooster comb HA (1 mg ml^-1). Detection of Mmp-9 transcripts was then performed by RT-PCR analysis.