KRT18 and lung cancer: In recent decade, KRT18 was suggested to be up-regulated in various human tumor tissues including lung cancer [15], invasive breast cancer [16], esophageal cancer [17], gastric cancer [18], hepatocellular carcinoma [19], bladder cancer [20], ovarian cancer [21], oral squamous cell carcinoma [22], pancreatic cancer [23], prostate cancer [24], and so on.