Abstract: Transducer of ErbB-2.1 （TOB1） encodes Tob1 protein which is a member of the BTG／TOB antiproliferative protein family. It is involved in regulating cell cycle progression through Ras／MAPK pathway and forming complex with CCR4Caf1 to inhibit cell proliferation. TOB1 as a tumor suppressor gene is closely related with tumor occurrence， development and metastasis. The decreased expression of Tob1 occurred in the majority of tumor. Its functional inactivation is associated with phosphorylation of accumulation and subcellular distribution， and the expression of TOB1 is associated with ionization sensitivity.