BIRC3 and thymoma: Significantly, anti-apoptotic BIRC3 – a member of the “IAPs” gene family that mainly blocks the extrinsic apoptosis pathway – was over-expressed at the mRNA and protein level in most TSCCs compared to type A and B3 thymomas; and BIRC3-positive 1889c thymic carcinoma cells showed stronger spontaneous apoptosis on BIRC3 knock-down in vitro than all other cell lines tested.