CD44 and esophageal squamous cell carcinoma: Next, western blot demonstrated that the expression of stemness‐associated transcription factors (c‐Myc and Sox2) and esophageal CSC markers (CD271, CD44, and Notch1) was increased in ESCC cells with QSOX2 overexpression and decreased in ESCC cells after QSOX2 knockdown (Figure 1G,H).