Sally,
I am not sure about tissue quality for protein analysis at -20 but in my
experience (I came from a Molec. Bio. Lab and we did a lot of RNA work)
RNA is still vulnerable to degradation at -20.  We did RNAse protection
assays and we stored all our samples both whole tissue and isolated
total RNA at -70.  So if you are doing insitu hybridization and looking
for an mRNA target you should store your tissue at -70, even for the
short term, just to be safe.  As I said, for protein targets I am not
sure but I do not think -70 would hurt.
Regards,
Dennis Sullivan


InnoGenex
www.innogenex.com

Sally Prouty wrote:
>
>  Is it okay to store frozen tissue samples at -20 instead of -70 for a
> couple of weeks.?
>
> Sally Prouty, HTL