To study the expression of a marker in a series of tissues or tumours, IHC using microarrays is convenient and allows to process large number of samples at once.
This is the way the group of Olsson et al. (2011) has recently demonstrated that various CD44 isoforms are expressed by breast cancers in correlation to the tumour type. The study was performed using 187 individual tumours using microarrays.
However, microarray is a fine and expensive tool, as quite some work is involved to make it. And it is, therefore, valuable. And, to perform IHC on arrays, the latter has to undergo thermalepitope recovery (as all material is formalin/fixed and paraffin embedded), which should be effective and gentle, not to loose the tissue and its morphology, but being able to stain the antigen of interest.
It is not by chance that Olsson et al used 2100 Retriever from Aptum for epitope recovery on arrays, as this may be the best Antigen Retriever on the market to the date.