Of note, increased succinate production is an inherent property of the CF lung, even in the absence of infection (22), due to a lack of sufficient membrane-bound CF transmembrane conductance regulator (CFTR) and impaired activity of the metabolic regulator Phosphatase and Tensin Homolog deleted on Chromosome 10 (PTEN) (22, 23). Here, CFTR is linked to cystic fibrosis.