The present invention provides that Ras-like, estrogen-regulated, growth inhibitor (RERG) is a malignant mesothelioma biomarker of clinical course and treatment sensitivity and, itself a target for mesothelioma treatment. A low RERG level in a mesothelioma subject indicates poor prognosis. Analyzing RERG expression level along can help mesothelioma patients make treatment choices. Furthermore, mesothelioma can be treated by modulating RERG activity, for example, with treatment with estrogen or estrogen-like agents.
