Given the increased expression of PSG9 in the mucosal cells of FAP patients that displayed lower β-catenin stabilisation compared to sporadic colorectal tumours in our study, it is possible that PSG9 is not directly regulated by the β-catenin/Wnt signalling pathway and that other molecules that regulate PSG9 expression are altered as a consequence of APC mutation. Here, APC is linked to colorectal neoplasm.