The function of ENSG00000154856 (APCDD1, APC down-regulated 1) is as follows. Negative regulator of the Wnt signaling pathway. Inhibits Wnt signaling in a cell-autonomous manner and functions upstream of beta- catenin. May act via its interaction with Wnt and LRP proteins. May play a role in colorectal tumorigenesis. {ECO:0000269|PubMed:12384519, ECO:0000269|PubMed:20393562}.