XIST and cancer: Recently, increasing studies have shown that XIST can function as a tumor suppressor gene or oncogene in different types of cancers, including nasopharyngeal carcinoma [14], non-small-cell lung cancer [15], esophageal squamous cell carcinoma [16], colorectal cancer [17], breast cancer [18], gastric cancer [19], cervical squamous cell carcinoma [20], pancreatic cancer [21], prostate cancer [22], bladder cancer [23], and so on.