I am working on skin cancer on female swiss albino mice. I am inducing skin cancer by topical treatment of DMBA and the other group DMBA+ cationic peptide treatment (Cationic peptide is given sc) I will be studying mainly the expression of apoptosis proteins bcl2,bax and cytochrome c. Want to know how can I preserve that for about 1 month this skin cancer tissues by liquid nitrogen and keeping in -20 degree deep freeze. whether it will be fine to preserve that way. plz help