CD44 and breast cancer: Among the CSC markers associated with breast pathology in humans are a high CD44/CD24 ratio, and elevated ALDH1 and CD49f markers.(53, 54, 55, 56) The CD44high/CD24low status is an indication of breast cancer cell malignancy and of proliferation and tumorigenesis capacity.(53) A very significant increase in CD24high cells (green) in PthlhKO cells was detectable by flow cytometry (Fig. 3A).