We describe fluorescence-based 2-D gel electrophoresis methods for visualization of low abundant cancer relevant tyrosine phosphorylated (pTyr) proteins The methods investigated were fluorescent Western blotting and two-dimensional difference gel electrophoresis (2-D DICE) for detection of non-enriched and immunoaffinity enriched pTyr protein patterns The same anti-phosphotyrosine specific antibody 4G10 was used for both approaches The results from fluorescent Western blotting of total proteins and from enriched CyDye DICE pre-labeled pTyr proteins showed similar down regulation of phosphorylation upon treating of cells from a cancer model system (K562 chronic myeloid leukemia cells) with imatinib This treatment introduced a known perturbation of phosphorylation that enabled testing of these new approaches to analyze variations in tyrosine phosphorylation levels Enrichment of pTyr proteins was found highly advantageous for the outcome Out of a simplified 2 D DICE experiment of immunoaffinity enriched control and treated pTyr proteins differential analysis as well as protein identification by mass spectrometry (MS) was possible (C) 2010 Elsevier Inc All rights reserved