BETA ACTIN?????

[Robert Stuart MD]

A protein sample in sample buffer is not unquantifiable provided it is
fairly concentrated.  The BCA protein assay (Pierce) is fairly robust to the
presence of SDS, easily up to 0.1%.  The amount of "blue" in all sample
ought to be the same.  Assuming the sample buffer is 2% SDS, and assuming
that the protein concentration is something like 10 ug/50 ul at a minimum
(for pretty gels), even the 20-fold dilution prior to assay would be ~0.01
ug/ul which is do-able with this assay.