Figure 2: Relevant bacterial systems and factors implicated in the regulation of P. aeruginosa biofilm formation. (1) Quorum sensing system; (2) Two-component regulatory system GacS/GacA and RetS/LadS (RR: response regulator domain receiver; P: phosphorylation) pathway; (3) Exopolysaccharides production and c-di-GMP pool regulation. See text for explanation.