HOTAIR and cancer: In addition to breast cancer [18], recent clinical evidences show HOTAIR is also involved in the progression of many other types of cancer, such as hepatocellular carcinomas (HCC) [19], colorectal cancer (CRC) [20], esophageal squamous cell carcinomas (ESCC) [21], suggesting that HOTAIR expression serves as a prognostic factor for tumorigenesis.