CD44 and gastric cancer: Various factors known to promote tumorigenesis were shown to increase MMP8 expression or activity in vitro: CD44- and CD24-expressing renal cell carcinoma stem cell subsets, serpinA1-expressing gastric cancer cells and CCL25-expressing ovarian cancer cells all showed higher migratory and invasive potential in vitro as well as higher MMP8 expression [143,144,145].