PF4 and infection: The trafficking of Pf4 reveals a covert form of cooperative interaction among P. aeruginosa cells within the community, because the extruded extracellular Pf4 filaments confer a number of benefits to the collective P. aeruginosa community, including structural support for biofilms, resistance to antibiotic exposure, increased survival in vivo during infection by promoting biofilm formation and reducing the host inflammation and immune response [25, 26, 44, 62, 63].