Dr. Genhong Cheng's laboratory studies molecular events involved in host defense against pathogen infections. Cheng and his colleagues have recently identified several gene programs specific for antiviral or antibacterial responses. In some cases, the researchers found that host responses to bacterial infection and viral infection may even be opposite. For example, type I interferon, an essential antiviral cytokine, might play a harmful role in host defense against certain bacterial infection. Cheng's laboratory also is interested in understanding the mechanisms of chemoresistance and developing novel strategies to improve cancer treatment. They have found that many chemotherapy agents commonly used clinically that are supposed to kill tumor cells can actually activate alternative cell survival pathways to protect tumor cells. This phenomenon may represent a potential mechanism of chemoresistance. Furthermore, Cheng and his colleagues found that blocking the NF- B-dependent up-regulation of Bcl-x and Bfl-1 genes can greatly reduce chemoresistance and sensitize chemotherapy-mediated apoptosis. Cheng's laboratory is currently evaluating the possibility of using the combination of NF- B inhibitors and chemotherapy agents for cancer therapy.