Proteins from PAXgene Tissue fixed, PAXgene Tissue fixed, paraffin-embedded (PFPE) and PAXgene Tissue fixed, cryo-embedded (PFCE) tissues are non-degraded, immunoreactive and have been successfully investigated by western blot analysis, reverse-phase protein arrays, two-dimensional gel electrophoresis (2D-PAGE), enzyme-linked immunosorbent assay (ELISA),and MALDI imaging mass spectrometry.