Strange bands in western of RPE-1 cells - (May/04/2009 )

Hello:

I have bought RPE-1 cells from ATCC, and I have a problem. When I make a western blot using extracts of these cells, in Ponceau I can see two strange bands one about 200 KDa, an another one more high.

Can anybody help me to identify these bands?, what is it?

Thanks in advange.

So you don't see these bands on Ponceau stained membranes using other cells? Ponceau is a non-specific protein stain so it could be anything. Are these cells known for producing some large protein in abundance? The only definitive easy way to ID them will be to extract the band from the gel and mass spec it.