Is a tagged protein more prone to degradation? (Lysis protocols??)

[Obaid Yusuf Khan]

I am trying to do a western blot with a protein which is tagged with a 
hemagglutinin antigen epitope tag. The western worked with the antibody but a 
second attempt failed, which I think is due to the tagged protein getting 
degraded during lysis of the tissue cultured cells. I will appreciate if anyone can 
tell me about a tested protein extraction protocol which uses protease inhibitors 
etc, or is specially employed for tagged proteins.
Thanks very much
Obaid Khan