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BSA or milk for blocking? - (Jan/12/2006 )

dear all,
I just wondered how do you block your blot, BSA or milk. I used milk before and it is fine, some collegues said they use BSA. how about you, any preference?
what is the con of BSA u use? I intended to try BSA, one of my blot using milk got quite lot background


usually BSA 3% is fine. but more expensive than milk.
sometime you may get some background with some secondary antibody (that's what is told I didn't have this experience yet) and then you should better use non fat dry milk 10%.
however, there are phosphotyrosine and biotine in milk, then you should avoid milk if you use an antiphosphotyrosine or streptavidine for detection.