CD82 antigen, also known as Kai-1, is a widely expressed palmitoylated molecule of the tetraspanin superfamily. KAI1/CD82 is localized on cell membrane and form interactions with other tetraspanins, integrins and chemokines which are respectively responsible for cell migration, adhesion and signaling. CD82/Kai-1 is a component of the promiscuous TIMP-1 interacting protein complex on the cell surface of human adenocarcinoma cells and gives insight into tumorigenic metastatic potential. CD82/Kai-1 suppresses EMT in prostate cancer cells adhered to fibronectin leading to reduced cell migration and invasiveness. CD82/Kai-1 function is important for muscle stem cell function in muscular disorders. Overexpression of CD82/Kai-1 suppresses growth, migration and invasion of oral cancer cells and may be considered as a potential therapeutic target in oral cancer.

CD82, also known as KAI-1, structurally belongs to tetraspanin family while categorised as metastasis suppressor gene on functional grounds. KAI1/CD82 is localized on cell membrane and form interactions with other tetraspanins, integrins and chemokines which are respectively responsible for cell migration, adhesion and signalling. Downregulation of CD82 expression is associated with the advanced stages of many human cancers and correlates with the acquisition of metastatic potential. Recent studies suggest that complex mechanisms underlie CD82 loss of function, including altered transcriptional regulation, splice variant production and post-translational protein modifications, and indicate a central role for CD82 in controlling metastasis as a 'molecular facilitator'. The loss of KAI1/CD82 expression in invasive and metastatic cancers is due to a complex, epigenetic mechanism that probably involves transcription factors such as NFkappaB, p53, and beta-catenin. A loss of KAI1 expression is also associated with the advanced stages of many human malignancies and results in the acquisition of invasive and metastatic capabilities by tumour cells. Thus, KAI1/CD82 is regarded as a wide-spectrum tumor metastasis suppressor.