BMI1 and cancer: Interestingly, we found that cell communication by a direct or an indirect manner resulted in distinct consequences, a direct co-culture of cancer cells with AMSCs showed a significantly enhanced potential malignancy of cancer cells, in comparison with the cancer cells cultured in the AMSCs conditional medium, as determined by the expression of stemness genes Oct4, Nanog, Bmi1 and Sox2. The role of Bmi1 and Nanog in regulating stemness and drug resistance of breast cancer cells has been verified [24].