UCA1 and gastric cancer: LncRNA UCA1 is reactivated in various malignant tumors including bladder cancer, breast cancer, cervical cancer, colorectal cancer, esophageal squamous cell carcinoma, hepatocellular carcinoma, gastric cancer, lung cancer, melanoma, ovarian cancer, thyroid cancer, tongue squamous cell carcinoma, prostate cancer, acute myeloid leukemia, glioma, pancreatic cancer and osteosarcoma [19–33].