MTSS1 and metastatic malignant neoplasm: Notably, MTSS1 is mostly expressed in normal tissues and in some non-metastatic cancer cell lines, however its expression is significantly decreased or mostly absent in many metastatic cancers including metastatic bladder cancer [6], prostate cancer [7], gastric cancer [8] and kidney cancer [9], suggesting that MTSS1 could function as an anti-metastatic protein.