Over-expression of anti-apoptotic cloned-genes is a widely used strategy for inhibiting apoptosis in mammalian cell culture. In our previous study, we reported Bombyx mori 30K gene improved the production of recombinant proteins in Chinese hamster ovary (CHO) cells. In this study, we reengineered the CHO cells with the 30Kc6 gene and 30Kc19 gene for the production of a therapeutic monoclonal antibody (mAb) directed against the glycoprotein receptor of human platelets. After the medium was changed from serum containing one to serum-free one, expression of 30Kc6 in CHO cells increased the cell viability by 40.8% in 4 days and mAb production by 2.3-fold in 5 days. However, no significant changes in cell viability and mAb production were observed for the cells expressing 30Kc19. In the case of the cells expressing 30Kc6, the specific production rate was also improved. The expression of the 30Kc6 gene increased the cell viability and productivity because it maintained the mitochondrial membrane potential (MMP) and reduced the downstream cascade responses for apoptosis. These results indicate that 30Kc6 outperformed 30Kc19 in terms of cell death-protective capability and the production of monoclonal antibodies in CHO cells. (C) 2010 Elsevier Ltd. All rights reserved.