PROM1 and cancer: Analyzing the association of post-therapeutic PD-L1 expression on CTCs with cancer recurrence, we found that patients with vulvar (Fig. 4E, left panel) or cervical cancer (Fig. 4F, left panel) with relapse exhibited significantly higher percentages of PD-L1+ CD49f+ CD133+ CTCs in their blood (purple background) in comparison to patients without recurrence (grey boxes).