MPEG1 and bacterial infectious disease: While Perforin-2 is present in bacteria-containing phagosomes (8, 9) and associated with the formation of pores on bacterial membranes (8), there are conflicting studies on the susceptibility of Mpeg1−/− mice to bacterial infection and on the contribution of Perforin-2 to the bactericidal capacity of phagocytes (8, 9).