Fig. 6. The HA-mediated induction of MMP-9 and MMP-13 is sensitive to actinomycin D, TPCK and emetine. MEFs were pretreated with either actinomycin D (A), TPCK (B) or left untreated before stimulation with rooster comb HA or TPA. For the detection of MMP-9 and MMP-13 mRNA equal amounts of total RNA from the cells were reverse transcribed and subjected to PCR amplification. As a control for equal amounts of cDNA, RT-PCR analysis of Gapdh was also performed. (C) 3LL cells were pretreated with 50 µM emetine for 45 min, then incubuated for 10 hours with 0.5 mg ml^-1 HA and 80 ng ml^-1 TPA as indicated. Poly(A)+ RNA was then prepared from the cells and analysed in a northern blot. Filters were hybridised with probes for Mmp-9, Mmp-13 and Gapdh.