Updated project metadata. Microgravity is one of the most important features in spaceflight. Previous evidence has shown that significant changes to the musculoskeletal and immune systems occurred under microgravity. The present study was undertaken to explore the change in protein abundance in human colon colorectal cells that were incubated for 48 or 72 h either in normal conditions and µG simulated conditions. The comparative proteomic method based on the 18O labeling technique was applied to investigate the up-regulated proteins and down-regulated proteins in SH-SY5Y under simulated microgravity.