Tyrosine phosphatase related to biofilm formation A (TpbA) is a DUSP from the pathogenic bacterium Pseudomonas aeruginosa. Infection by P. aeruginosa is one of the most common and life-threatening diseases faced by patients suffering from cystic fibrosis. 7 The persistence of P. aeruginosa infections is linked to its ability to form biofilms, organized communities of microorganisms encased in a polymeric matrix. 8 Critically, TpbA reduces biofilm formation in response to acyl homoserine lactone, a quorum-sensing molecule.6 TpbA is targeted to the periplasm and is a negative regulator of TpbB/YfiN, a diguanylate cyclase (GGDEF). TpbB catalyzes the synthesis of 3,5-cyclic diguanylic acid, an important second messenger that increases transcription across the pel operon, which, in turn, leads to the formation of pellicles, one of the major biofilms in P. aeruginosa. By attenuating the activity of TpbB through dephosphorylation of both tyrosine and serine/threonine residues, TpbA reduces the intracellular concentration of 3,5-cyclic diguanylic acid, which leads to a reduction in biofilm formation. 9 The essential role of TpbA in regulating P. aeruginosa biofilm formation makes it a potential drug target for P. aeruginosa infections.