Together with the tyrosine-protein kinase SYK, enhances production of the cytokine CXCL8/IL-8 via the NFKB pathway and may thus have a role in the intestinal immune response. Interacts (via extracellular domain) with PTPRH (via extracellular domain); the interaction dephosphorylates CEACAM20. Interacts (phosphorylated form) with SYK (via SH2 domains); the interaction further enhances CEACAM20 phosphorylation. Colocalizes with PTPRH and CEACAM1 at the apical brush border of intestinal cells. Strongly expressed in the small intestine and colon (at protein level) (PubMed:25908210, PubMed:26195794). Minimal expression in other tissues (at protein level) (PubMed:26195794). Highly expressed in cecum, colon, ileum, jejunum, and testis, and also detected at lower levels in salivary gland and thymus (PubMed:16139472). In intestinal epithelium, up-regulated in the presence of Gram-positive commensal gut bacteria. May also be up-regulated by interferon gamma (IFNG) and butyrate (a product of bacterial fermentation). Phosphorylated on tyrosine residues by SYK, SRC and FYN in vitro. Belongs to the immunoglobulin superfamily. CEA family.