The ubiquitous and oncogenic human herpes-virus Epstem-Barr virus (EB V) establishes a latent infection and promotes the long-term survival of the infected host cell by targeting the molecular machinery that controls cell fate decisions, including apoptosis, proliferation and differentiation. These host-virus interactions are likely to play a crucial role in the development of EBV-associated malignancies such, as Burkitt’s lymphoma, Hodgkin’s disease, nasopharyngeal carcinoma and tumours in lmmunosuppressed individuals. It has previously been shown in our laboratory that two EBV latent proteins, latent membrane protein 1 (LMP1) and EBV nuclear antigen 2 (EBNA2), which are major effectors of cellular phenotypic change, can independently regulate expression of the cellular bfl-1 gene Bfl-1 is an anti-apoptotic protein of the Bcl-2 family, whose preferential expression in hematopoietic and endothelial cells is controlled by inflammatory stimuli. In this study, it is reported that LMP1 and EBNA2 regulate bfl-1 activity through interactions with components of the NF-kB and Notch signalling pathways respectively NF-kB composed of p65 sub-units trans-activated the bfl-1 promoter m the EBV-negative cell line DG75, and an NF-icB-like binding site at position -52 to -43 relative to the transcription start site was essential for this effect. An RBP-Jk/CBF1 mutant blocked EBNA2-mediated trans-activation of bfl-1 in DG75 cells, indicating an important role for this DNA-binding protein in bfl-1 trans-activation by EBNA2. Although RBP-Jk/CBFI is also essential for signalling by the cellular equivalent of EBNA2, mtra-cellular Notch (NotchIC), this protein was not found to trans-activate the bfl-1 promoter. Both EBNA2 and LMP1 are expressed in EBVmfected cell lines, and EBNA2 is responsible for induction of LMP1 Blocking of either EBNA2- or LMP1-mediated signalling in EBV-mfected cell lines did not dramatically affect the level of bfl-1 promoter activity. However, when both EBNA2 and LMP1 signalling were blocked simultaneously, a significant decrease in the level of bfl-1 activity was observed. These data indicate a role for both EBNA2 and LMP1 in the regulation of the promoter for the bfl-1 gene m the context of the EBV-infected cell. These findings are relevant to our understanding of EBV persistence in the infected host, and its role in malignant disease.