These results confirm that uninfected NOKs stop proliferating, and spontaneously differentiate, when grown in monolayer cultures at sub-confluent conditions in the absence of EGF and BPE and demonstrate that both type 1 and type 2 EBV infection promote proliferation, and inhibit differentiation, under these growth factor-limited conditions. This evidence concerns the gene EGF and Epstein-Barr virus infection.