Figure 4A–C shows that treatment of esophageal cancer cells with HCQ results in the accumulation of autophagy marker LC-3II, indicating that autophagic flux is blocked. This result suggests that autophagy was successfully inhibited by HCQ. As expected, HCQ leads to a reduced level of the CD44+/CD24− CSC population (Figure 4D–F) and the number of spheres formed in 3D culture (Figure 4G–I), suggesting HCQ can inhibit cancer stemness. Here, CD44 is linked to esophageal cancer.