GCET1 (germinal center B-cell expressed transcript 1) belongs to the SERPIN family of proteins and is located within a cluster of SERPIN genes on chromosome 14q32). GCET1 is a protease inhibitor that inhibits trypsin and trypsin-like serine proteases in virto, and to a lesser extent inhibits plasmin and thrombin. This protein may play an important role in GC-B cell physiology. Its expression in lymphomas could be important in differential diagnosis and research.