The new CD44st mRNA and other CD44 isoforms. The filled circles represent constant regions. The areas circled represent exons selected for splicing that potentially give rise to many variable isoforms. The cytoplasmic domain of CD44 may bond to the cytoskeleton. The central region of the CD44 molecule mediates lymphocyte homing and the amino-terminal region links to the HA. The cytoplasmic domain, the transmembrane region, and HA binding region are highly conserved.[9-10, 19]. B) (1) Standard CD44, which lacks the entire variable region. (2) pMeta-1; Exons v4 to v7 were inserted in turn into the intermediate part of exons 5 and 17. (3) pMeta-2; Exons v6 and v7 were interposed between exons 5 and 17 . DNA sequencing confirmed that the reconstructed plasmid contained the sequence of the CD44st gene, which was composed of exons 1 to 4, exons 16 to 17, and 1 to 205 bases of 20 exons (Figure 1). The new gene sequence was sent to the National Center for Biotechnology Information (NCBI) for publication and registered with the number FJ216964.