CD44 and neoplasm: Moreover, at cut-off value ≥5% tumour cells with positive immunostaining, the expression CD44 was found to be accompanied by the co-expression with individual members of the HER family as well as EGFRvIII (83%), CD109 (16%), HER2/EGFRvIII (65%), or HER2/HER4/EGFRvIII (55%) (Table 3).