CD44 and gastric cancer: 41 discovered that IL‐18 expression was able to induce gastric cancer cell immune evasion by upregulation of CD44 and vascular endothelial growth factor in nude mouse gastric cancer xenografts, while Li et al. 42 reported that IL‐18 expression was upregulated after activation of the phosphatidylinositol 3‐kinase/serine–threonine kinase (Akt) signaling pathway in promotion of breast cancer metastasis.