PPP1R15A and cystic fibrosis: It is therefore of interest that expression of GADD34 reduced cell toxicity and increased cell survival upon iron deficiency caused by treatment with conditioned medium from P. aeruginosa. It has been shown that lungs of cystic fibrosis patients lack the ability to induce GADD34 [45], which might plausibly lead to increased cytotoxicity or altered innate immunity due to Pseudomonas infection of the lungs of CF patients.