THBS1 and glioma: To further understand the role of APOBEC3G in Smad2 deactivation in gliomas, we determined its role in mediating the expression of the Smad2-targeted genes Thrombospondin 1 (TSP-1), matrix metallopeptidase 2 (MMP2) and TIMP metallopeptidase inhibitor 1 (TIMP-1).