PROS1 and Epstein-Barr virus infection: On EBV infection, immortalised cells express the full panel of EBV latent genes that include the latent membrane proteins LMP1, 2A and 2B and the nuclear proteins EBNA-leader-protein, EBNA 1, EBNA 2, EBNA 3A, EBNA 3B and EBNA 3C.