Calretinin (CAB29, calbindin 2) is a calcium binding protein that belongs to calbindin family. It is mainly found in neuronal tissue, high expressed in auditory neurons. It has been implicated in as a calcium buffer, calcium sensor, and as a regulator of apoptosis (1). Calretinin is considered as a specific marker of mesothelllal cells; it is the only marker that has the utility in distinguishing between sarcomatoid mesotheliomas and sarcomatoid renal cell carcinomas (2). It is widely used in the panel of makers for distinguishing mesothlioma from adenocarcinoma. Along with calretinin, the panel includes E-cadherin, CEA, and cytokeratin 5/6 (3).

IHC