CD44 as a potential diagnostic tumor marker

CD44 molecular structure, a comparison between standard (CD44s) and variant (CD44v) forms. Illustration of the different exons of CD44. The upper green section shows a constant region of messenger RNA included in every possible variant. The red section is a variant exon that might be selected via alternative splicing of RNA. The lower shows the different domains of a CD44 molecule. The trans-membrane domain, which contains 269-289 amino-acids (a.a); then, the extracellular domain where the variant isoform is located with 292-300 a.a. The extracellular domain forms and the binding site for hyaluronate acid is structurally maintained by a disulphide bond.28 Copyright permission from Nature Reviews Cancer. Zöller M. CD44: can a cancer-initiating cell profit from an abundantly expressed molecule? Nat Rev Cancer 2011; 11: 254-267.