For instance, degradation of small RNAs by enzymes is responsible for poor penetration into tissues.24 Targeting CSCs with specific monoclonal antibodies to surface markers such as CD44 was proposed as a powerful approach to treat leukemia25 and possibly breast cancer.26 Unfortunately, eradication using specific monoclonal antibodies to surface markers was inappropriate as no common cell surface markers have been identified in Oct-4-expressing CSCs.14 Here, POU5F1 is linked to breast cancer.