In addition, the protein and mRNA expression levels of USP6NL, pluripotency and cancer stem cell markers (CD44 and CD133), transcription factor (Nanog and SOX2), and efflux transporter ABCG2 were significantly overexpressed in the U87MG-R and T98G-R sphere compared with the parental control (Figure 3D,E). Here, ABCG2 is linked to cancer.