Another factor essential for optimal M. marinum intracellular growth is the ESX-1 secretion system, responsible for the rupture of the phagosomes containing M. marinum and its release into D. discoideum cytosol at the end of this infection phase (21–37 hpi) (Hagedorn and Soldati, 2007; Hagedorn et al., 2009). Here, ESX1 is linked to infection.