[Protein-analysis] Formalin-fixation after snap freezing

[RWILLDMD from aol.com]

Hello,
 
I am new to histological protocols.  Recently, I completed an animal  study 
in which I harvested skin wounds and snap froze some of the samples  
anticipating in situ hybridization studies to complement/confirm quantitative  real time 
RT-PCR.  The tissue samples were stored at minus 20 (instead of  minus 80) 
and likely have degraded RNA.  
 
My question:  Is it possible to fix the previously frozen samples in  
formalin and continue analysis via immunohistochemistry for the protein  
(specifically proinflammatory cytokine) expression?   Also, does minus  20 storage 
(instead of minus 80) put the tissue at risk?
 
Thanks for your time.
 
Rich



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