Calretinin (CR; human gene symbol: CALB2) is a Ca2+-binding protein of the EF-hand family reported to be absent in normal mesothelial cells in situ; however in reactive mesothelial cells [3] and in malignant mesothelioma (MM), often resulting from asbestos exposure, CR expression is upregulated [3]. The gene discussed is CALB2; the disease is malignant mesothelioma.