**4. Conclusion(s)**

**Figure 5.** Nitrotyrosine immune activities in nitrosorcin-immunoprecipitated products from IV-astrocytoma and normal

**Figure 6.** Experimental data-based model of nitroproteins and their functions in human nonfunctional pituitary adenomas.

, nitroprotein. Reproduced from Zhan and Desiderio [11], with permission from Elsevier Science, copyright 2006.

NO<sup>2</sup> −

control (N) tissues. Reproduced from Peng and Zhan [35], with permission from springer, copyright 2015.

118 Electrophoresis - Life Sciences Practical Applications

Protein tyrosine nitration, as one of an important PTMs generated in nervous system tumor, participates in multiple complex biological processes, including cell proliferation and apoptosis, metastasis, migration, drug-resistance, cytoskeleton, signal transduction, immune response and cellular differentiation [43]. What is the mechanism for protein tyrosine nitration in carcinogenesis and development of malignant tumors? How to identify the protein targets and exact modified sites of tyrosine nitration? One/two-dimensional gel electrophoresis-based nitrotyrosine Western blot analysis and tandem mass spectrometry have been successfully applied in the analysis of nitroproteins in nervous system tumors.

Further study is needed to solve those limits on protein nitration: (1) Protein tyrosine nitration and heterogeneity of neoplasm. (2) Three-dimensional spatial structure of a nervous system tumor-related nitroprotein. (3) Consistency issues between body fluid and tissue. With the clarification of those issues on nitroproteins, protein tyrosine nitration will have a significant impact on the field of nervous system tumors.
