CD44 and breast cancer: For instance, an interesting experiment displays that ALDH (hi)CD44(+)CD24(−) and ALDH (hi)CD44(+)CD133(+) cells present with enhanced tumorigenicity and metastasis compared to ALDH(low)CD44(low/−) cells, indicating that high ALDH severs as an important role in the enhanced malignant and metastatic ability of breast cancer cells [38].