The concept of defective production of mediator precursors in CF is supported by correlation analysis, as the releases of the [14C]DHA and the [3H]AA correlate in CF group in resting condition, whereas in CT group the same correlation is observed only after stimulation with GM-CSF, indicating that both the basal response and the mechanisms regulating precursors liberation are altered in the CF patients. The gene discussed is CSF2; the disease is cystic fibrosis.