Problem whith b-actin bands - (Mar/10/2006 )

I found a papper that shows a immunobloting in witch b-actin was used as an internal control.

The problem is that insted of one band (as I expected) I find two bands for b-actin, one right beneath the other.

Is this normal?

I find this very strange, especialy because they do a densitometric analysis of the blot.
Can anyone comment on this?

Thanks

no....
but i am not sure if the monoclonal or polyclonal will make a diff. I use mouse-mono and i always find a single band..