CD44 and breast cancer: We sorted CD24−CD44+ breast CSCs from the patient-derived Luc2-eGFP (L2G)-labeled breast triple-negative (TN1) cancer cells 6 as well as in the murine breast cancer 4T1 cells (Figure s1 A), and found a significantly higher USP22 expression in breast CSCs compared to that in the CD24+CD44− non-CSCs by western blotting (Fig. 1A & 1B and Figure s1 B).