**4.2 Expression and significance of tissue protein in patients with Endometriosis**

In 2006, Kyama et al. [5] used SELD I-TOF-MS technology to find that the expression of proteins and peptides in the eutopic endometrium of patients with endometriosis weight range of 2.8–12.3 kDa was 3–24 times lower than the molecular with non endometriosis. The expression of proteins and peptides in the lesions of patients with endometriosis had a tendency to increase within the molecular weight range of 3–96 kDa, and especially an up-regulated cluster of proteins between 22 and 23 kDa, identified to be transgelin, a smooth muscle actin-binding protein. In 2007 Fowler et al. [94] used 2-DE and peptide mass (MS) technology to confirm that the protein associated with endometriosis. Several deregulated proteins are identified: (1) chaperones and calcium binding proteins include heat shock protein 90 (HSP90) and annexin A2. (2) Cell oxygenation status related to protein, such as peroxiredoxin and thioredoxin-1, -2 (thioredoxin reductase-1, -). (3) Proteins associated with protein/DNA synthesis/decomposition, such as nucleoside diphosphate reductase, prohibitin, and proline-4-hydroxylase. (4) Secreted proteins, such as apolipoprotein A1. (5) Structural proteins such as vimentin and actin, whose function suggests that they play a role in the pathogenesis of endometriosis. At the same time, it was believed that the differentially expressed protein spots produced are identical whether the lysate of the endometrium was aggregated or isolated. Immunohistochemistry, Western blotting, and biological effects were also used to validate differential proteins and achieve desirable results. This study demonstrated that 2-DE gel analysis and mass spectroscopic protein identification are suitable for the identification of proteins with candidate associations with endometriosis.
