To identify the molecular mechanism of MTA2 in the invasive behaviour of RCC, western blot analysis, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay, and gelatin zymography demonstrated that MTA2 knockdown significantly decreased the protein, mRNA, and activity expression of MMP-9 in 786-O, Caki-1, and ACHN cells, but was not involved in MMP-2 (Figure 4A–C). The gene discussed is MMP2; the disease is renal cell carcinoma.