western blot normalization - (Jun/20/2008 )

Hi,
I have a question about western blot normalization. My samples are human liver microsomes, and I need to normalize the band intensity with house-keeping-gene products. Normally, people use beta-actin or GAPDH to normalize the band intensities, but both beta-actin and GAPDH are cytosolic protein. I do see some people normalize with beta-actin for microsomal proteins, but to me, it is not the right way to normalize it... If you use beta-actin to normalize your microsomal protein, could you please give me your rationals? If you use other house-keeping-gene product to normalize your microsomal proteins, what are they?
Thank you for your help!!