HBx-induced tumor cell invasion is dependent on metalloproteinase activity, and HBx upregulates activated MMP-2 expression. (a) CMO and CMX cells were allowed to invade a Matrigel-coated Transwell in the presence of the MMP inhibitor BB-3103 or DMSO as a control. The invasion was quantified as in Figure 1. (b) Cells were grown for 24 hours in serum-free medium, and gelatin zymography analysis of the cell culture supernatants of PMA-stimulated human umbilical vein endothelial cells (control) and the different hepatic cell lines was performed. (c and d) CMO and CMX (c) or HepG2 and 2.2.15 (d) cell lysates and supernatants were analyzed for MMP-2 and MMP-9 expression by Western blot. Anti–α-tubulin and anti-albumin mAb’s assure equal protein load in all lanes.