CD44 and breast cancer: In addition, CD44 also exerts significant effects on caner invasion and metastasis of various tumor types [27], such as lung adenocarcinoma [18], breast cancer [28–30], neuroblastoma [31], gastric cancer [32], esophageal squamous cell carcinoma (ESCC) [33], colorectal cancer [34–37], prostate cancer [38], nasopharyngeal carcinoma [39], endometrial cancer [40], clear cell renal cell (RCC) carcinoma [41], pancreatic cancer [42], meningioma [43] and ovarian cancer [44].