Abstract: 【Abstract】 Objective To determine the expression of proteasome aotivator γ (REGγ) in human lung cancer tissues and cell lines and its association with malignant biological behaviors. Methods Immunohistochemistry (IHC) was used to detect the expression of REGγ in lung cancer and normal lung tissues. The expressions of REGγ in lung cancer cells and normal epithelial cells were determined by Western blot. The H1975 lung cancer stable cell lines with different levels of REGγ expression were constructed and their proliferations were evaluated by MTT assay. PI staining was used to assess the influence of REGγ on cell growth cycle. The effect of REGγ on the migration of lung cancer cells were observed with the cell scratch experiment. Results Lung cancer tissues had significantly higher levels of REGγ expression than normal tissues. Similarly, lung cancer cell lines showed higher levels of REGγ expression than the normal epithelial cell line. The overexpression of REGγ enhanced cancer cell proliferations (P<0.05), promoted more cells into the S+G ₂/M phase (P<0.05) and promoted the migration of cancer cells (P<0.05). All of these effects were reversed after suppression of REGγ. Conclusion REGγ facilitates malignant biological behaviors of lung cancers.