multiple bands on WB - b-actin blots show multiple bands!!! (Mar/30/2006 )

Hi all,
I had been using b-actin as loading control, but recently have started to get multiple bands at different MW. Now at 38kd the bands are very strong and distinct whereas bands close to 50 kd ( expected b-actin) shows unequal protein levels, not very distinct and somewhat weak bands because of which can not understand the levels of loading.

Please any suggestions are welcomed!!!

Are you still using the same old cell extract? If so you might be getting degradation products. If not then I can only suggest there's a problem with your assay. I routinely use beta-actin as a control an d only get a single band at 42 kDa.