Consistent with our hypothesis, we found that stemness-related genes involving in ABCG2, SOX9 and NANOG were enriched in KYSE410 and KYSE450 spheroids compared to adherent ESCC cells, as well as YAP, which has a higher expression status in ESCC stem-like cells than the differentiated ESCC cells (Fig. 3a). Here, SOX9 is linked to esophageal squamous cell carcinoma.