In addition, the National Center for Biotechnology Information (NCBI) GenBankH database (http://www.ncbi.nlm.nih.gov/ genbank) was searched for splice variants of CEA. A single splice variant (NCBI accession number CR749337) from colon cancer tissue was identified. This transcript uses an alternative splice donor site in exon 2 and skips exons 3 and 4; thus, the translation of the transcript results in a 420 aa protein with an in-frame truncation from amino acids 116 to 396 of the full-length CEA. This truncation deletes a small portion of the N-terminal domain, the entire A1 and B1 domains, and a large portion of the A2 domain (Figure 1, 2) . The splice variant sequence codes for the same 34-aa processed leader sequence and C-terminal 17-aa peptide which is expected to be removed during GPI linkage in a similar manner as full-length CEA, and, after undergoing similar post-translational modifications as full-length CEA, is predicted to be a mature, GPI-anchored membrane protein of 369 amino acids.