Inversely to the 2-DE observation, the protein level of ENO1 showed a 1.5 fold reduction in 35.3% of GC samples compared to their paired controls by western blot. Only one sample presented a 1.5 fold increase. However, we only selected the spots differentially expressed with a 1.5 fold change between groups for the mass spectrometry analysis. These selection criteria may lead to the lack of correlation between western blot and proteomic analyses. Thus, other spots of ENO1 may present a slight reduced expression, but with a high impact in the mean of this protein expression. Our results show that different spots may be regulated differently inside a heterogeneous gastric sample. Our findings also highlight that the metabolic phenotype is not universal in tumor cells, especially considering that different cell clones are present inside a single 3,4,5-Trimethoxyphenylacetic acid cancer sample. Even in glycolytic tumors, oxidative phosphorylation is not completely shut down. Owing to the dynamic nature of the tumor microenvironment, it is suggested that the metabolic phenotype of tumor cells changes to adapt to the prevailing local conditions. The regulation of this metabolic flexibility is poorly understood. However, the feedback control between MYC and ENO1, as well as MBP1, may have a key role in this process since the MYC oncogene may stimulate both glycolysis and oxidative phosphorylation. However, these authors described that ENO1 immnuoreactivity seems to be significantly more intense in GC cells than non-neoplastic cells and its positive expression tends to be associated with poor prognosis. This in part corroborates 
our results that demonstrate that the level of ENO1 protein seems to be reduced more frequently in less invasive cancer samples. HSPB1 was selected for further investigation also due to its protective function against 4-(Benzyloxy)phenol infection and cellular stress. HSPB1 is one member of the family of heat shock proteins that is characterized as molecular chaperones. In addition to its chaperone function, HSPB1 also seems to be an important regulator of structural integrity and membrane stability, actin polymerization and intermediate filament cytoskeleton formation, cell migration, epithelial cell-cell adhesion, cell cycle progression, proinflammatory gene expression, muscle contraction, signal transduction pathways, mRNA stabilization, presentation of oxidized proteins to the proteasome, differentiation, and apoptosis. HSPB1 is highly induced by different stresses such as heat, oxidative stress, or anticancer drugs. In non stressed cells, HSPB1 is not expressed or at very low levels. Once induced, HSPB1 acts at multiple points in the apoptotic pathways to ensure that stressinduced damage does not inappropriately trigger cell death. Many cancer cells have markedly increased HSPB1 levels, and this protein expression contributes to the malignant properties of these cells, including increased tumorigenicity and treatment resistance, and apoptosis inhibition. Overexpression of HSPB1 has been described in several tumors and it has been reported as an indicator of poor prognosis. Elevated HSPB1 expression in neoplastic cells plays a key role in protection from spontaneous apoptosis in response to anticancer therapy and leading to tumor progression and resistance to treatment. In the present study, we observed one spot of the HSPB1 protein that presented a higher expression in GC compared to controls by 2-DE analysis, corroborating previously proteomic studies with GC patients from Asiatic countries. Here, no association was observed among HSPB1 expression and clinicopathological characteristics in the present study. However, HSPB1 was previously associated with gastric tumor size, distant metastasis, lymph node state and pStage in other populations. Despite the fact that HSPB1 expression was not associated with any clinicopathological characteristic in our population.