APC and cancer: WNT pathway activation in human cancers is associated with gene mutations such as APC mutations [36, 37], AXIN mutations and beta-catenin mutations [38], epigenetic modifications such as methylation of the WNT negative regulator and secreted Frizzled-related proteins (SFRPs) [39] and positive or negative feedback control of gene expression in WNT/beta-catenin pathways.