CD44 and cancer: Given the activity of ALDH family is a marker of CSCs in many solid cancers and CSCs are a risk factor for carcinogenesis and responsible for tumor initiation, growth, metastasis [31], we examined the effect of ALDH1B1 silencing on the protein expressions of cancer stem cell markers, including Nanog, Sox2, Oct-4, CD44, Notch-1 and Notch-3, in osteosarcoma cells.