Abstract: Objective: To detect the Nucleostemin (NS) gene expression in some tumor cells, and study the effect of NS in cell proliferation. Methods: Cervical cancer cells, breast cancer cells, ductal carcinoma, hepatoma cells (SMCC7721), hepatoma cells (HpeG2) and normal liver cells were cultured in vitro. Cells in logarithmic growth phase were collected and total RNA was extracted from 6 kinds of cultured tumor lines. The NS differential expression level was measured by RT-PCR and western blotting. Results: All tumor cells in a high level of NS gene expression,especially SKRB-3 breast cancer cells,breast ductal carcinoma T47-D cells,hepatoma SMCC-7721 and HepG2 cells had the highest expression of NS gene, and no NS expression was detected in normal liver cells. Conclusions: NS is highly expressed among all kind of tumor cells is universality,and no expression in terminally differentiated normal liver cells. NS genes could involve in tumor cell proliferation regulation,which provided new method and target for cancer gene therapy and gene diagnosis.