Tumor suppressor. Promotes rapid degradation of CTNNB1 and participates in Wnt signaling as a negative regulator. APC activity is correlated with its phosphorylation state.

Activates the GEF activity of SPATA13 and ARHGEF4. Plays a role in hepatocyte growth factor (HGF)-induced cell migration. Required for MMP9 up-regulation via the JNK signaling pathway in colorectal tumor cells.

Associates with both microtubules and actin filaments, components of the cytoskeleton (PubMed:17293347). Plays a role in mediating the organization of F-actin into ordered bundles (PubMed:17293347). Functions downstream of Rho GTPases and DIAPH1 to selectively stabilize microtubules (By similarity).

Acts as a mediator of ERBB2-dependent stabilization of microtubules at the cell cortex. It is required for the localization of MACF1 to the cell membrane and this localization of MACF1 is critical for its function in microtubule stabilization

Forms homooligomers (Probable). Found in a complex consisting of ARHGEF4, APC and CTNNB1 (PubMed:10947987). Found in a complex composed of MACF1, APC, AXIN1, CTNNB1 and GSK3B (By similarity).

The complex composed, at least, of APC, CTNNB1 and GSK3B interacts with JPT1; the interaction requires the inactive form of GSK3B (phosphorylated at 'Ser-9') (PubMed:25169422). Interacts with APC2 (PubMed:11691822). Interacts with DLG1 (via PDZ domains) and DLG3 (via PDZ domains) (PubMed:8638125, PubMed:9188857).

Interacts with alpha- and beta-catenins (PubMed:8259519). Interacts with AXIN1 (via RGS domain) (PubMed:10811618). Interacts with ARHGEF4 (via N-terminus) (PubMed:10947987).

Interacts (via C-terminal residues 2674-2843) with MAPRE1 (via C-terminal residues 206-211); the interaction inhibits association with and bundling of F-actin (PubMed:14514668, PubMed:17293347, PubMed:19632184). Interacts with MAPRE2 and MAPRE3 (via C-terminus) (PubMed:14514668). Interacts with DIAPH1; DIAPH1 acts as a scaffold protein for MAPRE1 and APC to stabilize microtubules and promote cell migration (By similarity).

Interacts with DIAPH2 (By similarity). Interacts with SCRIB; may mediate APC targeting to adherens junctions of epithelial cells (PubMed:16611247). Interacts with SPATA13 (via N-terminus and SH3 domain) (PubMed:17599059).

Interacts with ASAP1 (via SH3 domain) (PubMed:20509626). Interacts (at the cell membrane) with AMER1 and AMER2 (via ARM repeats) (PubMed:21498506, PubMed:22128170). Interacts with KHDRBS1 (PubMed:22000517).

Interacts with actin; binds both to F-actin and actin filament bundles (PubMed:17293347)

Expressed in a variety of tissues: brain, small intestine, colon, thymus, skeletal muscle, heart, prostate, lung, spleen, ovary, testis kidney, placenta, blood and liver (PubMed:21643010, PubMed:27217144). Isoform 1A: Very strongly expressed in brain but has relatively low expression levels in other tissues (PubMed:19527921, PubMed:21643010, PubMed:27217144). Isoform 1B: Predominant form in all tissues except for brain, including gastric mucosa and blood (PubMed:19527921, PubMed:21643010, PubMed:27217144)

The microtubule tip localization signal (MtLS) motif; mediates interaction with MAPRE1 and targeting to the growing microtubule plus ends

The basic region (residues 2167-2674) mediates the association with both microtubule and actin proteins and promotes the bundling of F-actin

• Familial adenomatous polyposis 1 (FAP1)

  An autosomal dominant cancer predisposition syndrome characterized by adenomatous polyps of the colon and rectum, but also of upper gastrointestinal tract (ampullary, duodenal and gastric adenomas). This is a viciously premalignant disease with one or more polyps progressing through dysplasia to malignancy in untreated gene carriers with a median age at diagnosis of 40 years.

• Desmoid disease, hereditary (DESMD)

  An autosomal dominant disease characterized by multifocal fibromatosis of the abdominal wall and mesentery. Desmoid tumors can also affect paraspinal muscles, breast, occiput, arms, and lower ribs.

• Medulloblastoma (MDB)

  Malignant, invasive embryonal tumor of the cerebellum with a preferential manifestation in children.

• Gastric cancer (GASC)

  A malignant disease which starts in the stomach, can spread to the esophagus or the small intestine, and can extend through the stomach wall to nearby lymph nodes and organs. It also can metastasize to other parts of the body. The term gastric cancer or gastric carcinoma refers to adenocarcinoma of the stomach that accounts for most of all gastric malignant tumors.

  Two main histologic types are recognized, diffuse type and intestinal type carcinomas. Diffuse tumors are poorly differentiated infiltrating lesions, resulting in thickening of the stomach. In contrast, intestinal tumors are usually exophytic, often ulcerating, and associated with intestinal metaplasia of the stomach, most often observed in sporadic disease.

• Hepatocellular carcinoma (HCC)

  A primary malignant neoplasm of epithelial liver cells. The major risk factors for HCC are chronic hepatitis B virus (HBV) infection, chronic hepatitis C virus (HCV) infection, prolonged dietary aflatoxin exposure, alcoholic cirrhosis, and cirrhosis due to other causes.

• Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS)

  A familial gastric polyposis syndrome characterized by autosomal dominant transmission of fundic gland polyposis with occasional hyperplastic and adenomatous polyps, sparing of the gastric antrum, and a significant risk of intestinal-type gastric adenocarcinoma development. Colorectal polyposis is not observed, and family history does not include colorectal cancer.