Fig. 3.

Doxycycline does not affect tumour necrosis factor (TNF)-α-induced matrix metalloproteinase (MMP)-9 expression. (a) Mouse vascular smooth muscle cell line (MOVAS) cells were cultured in medium alone, medium containing 20 ng/ml TNF-α, or TNF-α plus various concentrations of doxycycline for 6 h. MMP-9 gene expression was determined by real-time polymerase chain reaction (PCR) and normalized to GAPDH. Data is presented as the mean ratio ± standard error of the mean of triplicate cultures (representative of six independent experiments). (b) MOVAS cells were serum-starved for 48 h prior to culture in serum-free medium alone, medium containing 20 ng/ml TNF-α, or TNF-α plus various concentrations of doxycycline for 18 h. Supernatants were collected and immunoblotted for MMP-9 protein (representative of two independent experiments).