POU5F1 and esophageal squamous cell carcinoma: As we have previously reported, SOX2OT is spliced into several transcript variants, including SOX2OT, SOX2OT-S1, and SOX2OT-S2 which co-upregulated with master regulators of pluripotency, SOX2 and OCT4, in esophageal squamous cell carcinoma (ESCC).