Mutations or over expression of the p53 negative regulator (MDM2) could cause p53 inactivation observed in BL cells. Reactivation of the p53 in these EBV - BL cells can be caused by decreasing the amount of MDM2 14. This has been shown to lead to nutlin-3 inducing apoptosis. Nutlin-3 is an antagonist to MDM2 leading to the reactivation of p53 in all of the BL cells 14. The level of apoptosis caused by nutlin-3 was responsible for the level of activation induced in p53. The EBV status of the cell dictated the amount of responsiveness to the change in p53 14. Cells which were classified as being a latency III type as well as being positive for EBV were more resistant to the change back to activation of p53 14. Latency I EBV and BL cells were more sensitive due to nutlin-3 14.