For instance, reduced expression of FOXK2 has been linked to tumor suppression in breast cancer (23, 50), cervical cancer (51), glioma (52), gastric cancer (53), ESCC (40), non-small cell lung cancer (NSCLC) (54), and clear-cell renal cell carcinoma (ccRCC) (29), while FOXK2 expression was significantly upregulated in colorectal cancer (17, 41, 42), ovarian cancer (55) and hepatocellular carcinoma (37, 56) (summarized in Table 1). Here, FOXK2 is linked to esophageal squamous cell carcinoma.