- Modified vaccinia virus Ankara protein F1L is a novel BH3-domain-binding protein and acts together with the early viral protein E3L to block virus-associated apoptosis. Fischer, S.F., Ludwig, H., Holzapfel, J., Kvansakul, M., Chen, L., Huang, D.C., Sutter, G., Knese, M., Häcker, G. Cell Death Differ. (2006)