Unraveling the roles of CD44/CD24 and ALDH1 as cancer stem cell markers in tumorigenesis and metastasis.

CD44/CD24 and ALDH1 are widely used cancer stem cell (CSC) markers in breast cancer. However, their expression is not always consistent even in the same subtype of breast cancer. Systematic comparison of their functions is still lacking. We investigated the expression of CD44, CD24 and ALDH1 in different subtypes of breast cancer cells, and explored their relationship with cancer progression. We defined a parameter CD44/CD24 ratio to present the expression level of CD44 and CD24 and found that high CD44/CD24 ratio and ALDH1