Phagosomal escape of F. tularensis. Colocalization of GFP-expressing F. tularensis strains and LAMP- 1. J774 cells were infected for 2 h with F. tularensis strains expressing GFP (Green fluorescent protein) and, after washing, incubated for indicated time points. Fixed specimens were labeled for the late endosomal and lysosomal marker LAMP-1. 100 bacteria were scored per sample and time point. Results from a representative experiment are shown. Bars represent mean values and error bars are used to indicate standard deviations. Asterisks indicate that the colocalization differs significantly from that of LVS (*: P < 0.05; **: P < 0.01).