According to paper by van der Loos 2007, Ki67 staining can work when fixated in formalin for up to 1 year . Use Tris-EDTA pH9 for antigen retrieval. I don't know about TUNEL.

We prefer fixation in 48% ethanol, 7% PEG300 for at least 48h but it can be left for months. There are many alternatives for formalin fixation, see for example doi: 10.1016/j.ymeth.2014.01.022.

Like Bouke said, the key here is antigen retrieval. I would first stain a few of your samples according to normal protocol, and if they are not successful, compare pH6 Citrate buffer, pH9 Tris-EDTA and proteinase K. At least one of these three methods should do the unmasking sufficiently. You can find a lot of info here: http://www.ihcworld.com/epitope_retrieval.htm

Yes of course you can. Formalin fixed tissue lasts very long.

Unless it is a very special epitope, but the proteins you mentioned are ok.

best wishes,

Teresa

Hi Bouke, Nora and Teresa,

Thanks for your suggestions. We will go ahead with the Ki67 and TUNEL IHC on the tumor sections. We will try with Tris-EDTA pH9 for antigen retrieval.

Thank you all again.