MMPs expression in HCC cells under the stimulation of soluble CD147. Eukaryotically expressed extracellular CD147 (E-CD147ECD), serum-free conditioned medium, and SMMC-7721 cell lysates were subjected to western blotting. HAb18 reacting against extracellular CD147 (A) and C-19 reacting against intracellular CD147 (B) were used respectively. (C) Real-time PCR was performed to test mRNA levels of MMP-1, -2, -3, -9, and MMP-13 in SMMC-7721 cells in the absence or presence of 10 μg/ml E-CD147ECD for 6 h. (D) Soluble CD147 increased the expression of MMP-2 in a concentration-dependent manner. SMMC-7721 cells were treated with different concentrations of E-CD147ECD for 6 h and MMP-2 mRNA level was analyzed using real-time PCR. (E) SMMC-7721 cells were treated with different concentrations of E-CD147ECD and MMPs levels were analyzed using gelatin zymography. (F) SMMC-7721 cells were treated with prokaryotically expressed extracellular CD147 (P-CD147ECD) or E-CD147ECD for 6 h and MMP-2 mRNA level was analyzed using real-time PCR. GAPDH was used as a normalization control. *P < 0.05. (G) Real-time PCR showed mRNA level of MMP-2 in SMMC-7721 cells treated with P-CD147ECD or prokaryotically expressed intracellular CD147 (P-CD147ICD) for 6 h. GAPDH was used as a normalization control in all real-time PCR analysis. *P < 0.05, **P < 0.01.