Fig. 3— a) Conditioned medium from airway myocytes serum-deprived for 3, 6 and 9 days. Proteins were separated by sodium dodecyl sulphate–polyacrylamide gel electrophoresis, transferred onto nitrocellulose, probed with anti-matrix-metalloproteinase (MMP)-2 antibody (1:1000) via Western blot. This representative blot shows that accumulation of MMP-2 began at day 3 of serum-deprivation, and increased with duration of serum-deprivation. b) A similar sample to that shown in (a), subjected to gelatine substrate zymography (performed in triplicate). This representative zymogram shows an ∼70 kDa band of metalloenzyme proteolytic activity, corresponding to MMP-2 that showed increased activity beginning at day 3 of serum-deprivation, and increased with duration of serum-deprivation.