NT-proBNP was abundant in the effusions of mesothelioma patients and was particularly high in those with impaired NF2 expression.<h4>Conclusions</h4>NPPB, whose levels can be measured in pleural effusions of mesothelioma patients, has the potential to act as a biomarker to detect NF2-Hippo pathway gene alterations and/or predict patient prognosis. The gene discussed is NPPB; the disease is mesothelioma.