ABCG2 and head and neck squamous cell carcinoma: Second, the sorted EpCAM+/ABCG2+ cells of patients 6, 8-10, and 12 expressed genes specific to the TSD phenotype (Figure 2E) including the core transcription factors associated with the MYC-HIF-2alpha stemness pathway (20), the CSC markers of HNSCC including CD44v6, ALDH1 and BMI, the immunosuppressive molecules PDL1, as well as the autocrine growth factor receptors VEGFR1, CXCR4, EGFR, and TLR 2/4.