Hello,

I'm currently doing gelatin zymography for different human glioma cell lines.

In the supernatatants from these cells, I observed the well known bands for MMP2 and MMP9 at around 70 kDa and 90 kDa, respectively.

In the cell lysates, however, the strongest band had a molecular weight of about 45 kDa (see attached picture). Does anyone know what this band is?

Thank you!

P.S. the lysates were prepared as follows:

- wash cells 2x PBS (without Ca/Mg)

- resuspend cell pellet in 100µl PBS (without Ca/Mg)

- 3 freeze/thaw cycles with vigorous vortexing in between

- centrifuge at 15000 RPM, 10 min, 4°C to get rid of cell debris

- transfer supernatant in a fresh tube and mix with Zymogram Sample Buffer

- run on gel immediately