To investigate the effect of hyper-pressure on retinal ganglion cells (RGC-5), RGC-5 cells were exposed to an ambient hydrostatic pressure of 100 mmHg. Upon treatment, the proliferation of RGC-5 cells was inhibited and neuronal apoptosis was detected by specific apoptosis marker TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling). To probe into the mechanism mediating the apoptosis of RGC-5 cells in 100 mmHg, protein profile alterations following hyper-pressure treatment were examined using two-dimensional gel electrophoresis (2-DE) followed by MALDI-TOF. Out of the 400 protein spots of RGC-5 cells detected on 2-DE gels, 37 differentially expressed protein spots were further identified using in gel tryptic digestion and mass spectrometry. Among these proteins, glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) was significantly expressed 10 times more in 100 mmHg than in normal pressure. The accumulation of GAPDH in the nucleus and its translocation from the cytosol to the nucleus in 100 mmHg were observed using a microscope. These results suggest that the hyper-pressure-induced apoptosis in RGC-5 cells may be involved with not only the increase of GAPDH expression, but also the accumulation and the translocalization of GAPDH to the nucleus.