CTSK and neoplasm: Based on the analysis in the TCGA GTEx pan-cancer dataset (N = 19,131, G = 60,499), it could be observed that CTSK gene was significantly higher-expressed in 17 cancers such as LUAD, STES, STAD, KIRC, LUSC, LIHC, PAAD, CHOL than their adjacent normal tissues, and that another 10 tumors were observed to be significantly down-regulation, such as UCEC, BRCA, ACC, PRAD, THCA, KICH.CTSK expression was observed to be elevated in tumor tissues in 23 cancer species (Fig. 5).