KRT5 and mesothelioma: Double-stained sections were obtained to highlight colocalization of CK5/6, a high molecular weight keratin, with both calretinin, a calcium binding protein closely linked to mesothelioma (Fig. 2b and e), and with thrombomodulin (also called CD141), a well-established marker for mesothelioma27–30 (Fig. 2c and f).