SDS-PAGE gelatin and plasminogen zymography of plasma from db/db and db/+ mice. Plasma from db/+ (C1 and C2) and db/db (D1 and D2) mice was subjected to gelatin zymography with 10% polyacrylamide in the gels (a). For better separation in the higher molecular weight areas, the samples were also run on 7.5% polyacrylamide gels (b). The same samples were further subjected to gelatin and plasminogen zymography to detect both gelatinases and plasminogen activators (c). Standards used were S1 with pro-MMP-2, (72000), pro-MMP-9 monomer (92000), and pro-MMP-9 homodimer (225000), S2 (conditioned medium from the monocytic cell line THP-1) containing pro-MMP-9 monomer (92000) and pro-MMP-9 homodimer (225000), and plasminogen activator (55000) and S3 containing trypsin (24000). The gels were stained with Coomassie blue, and white areas indicate gelatinases. The arrow in panel C shows the position of a plasminogen activator in mouse plasma samples. These zymograms are representative for all the 20 plasma samples investigated.