H2AX and esophageal squamous cell carcinoma: Our results indicated that treatment with selenium compounds reduced the number of γ-H2AX foci after 1 day in three ESCC cell lines and prolonged incubation with selenium compounds for 3 days, causing a significant reduction in the number of γ-H2AX foci per cell as compared to the untreated cells: KYSE 150 (Figure 5C–E), KYSE 520 (Figure S3A–D) and CSEC 216 (Figure S3E–H).