Ying Zhi L, et al. - Researchers assessed how the invasive ability of human breast cancer MCF-7 cells was influenced by hyaluronic acid (HA)-CD44st, using MCF-7 cells transfected with the eukaryotic expression vector pcDNA3.1-CD44st (MCF/CD44st). In postoperative breast cancer patients, they also investigated the correlation between the expression of CD44st and human epidermal growth factor receptor-2 (HER-2). They noted that the invasiveness of MCF-7 cells might be regulated by binding HA to the CD44st receptor. This effect was attributed to the CD44st/transforming growth factor β (TGFβ)/phosphatidylinositol-3-kinase (PI3K)/AP-1 signaling pathway with an increased expression of TGFβ and HER-2. In postoperative breast cancer patients, the correlation of CD44st mRNA expression with HER-2 expression was observed.