NCOA6 knockdown blocked the activation of NF‐κB‐mediated MMP9 transcription. A, The gelatinolytic activity of secreted MMP9, but not of secreted MMP2, was significantly impaired after NCOA6 was knocked down. B, The transcription of MMP9 was also significantly attenuated after NCOA6 was knocked down, while the transcription of TIMP1 was enhanced. The transcription of MMP2 and its inhibitor TIMP2 showed no change. C, Knockdown of NCOA6 not only significantly decreased the basic reporter activity of the MMP9 promoter but also blocked the increased reporter activity of the MMP9 promoter induced by RELA/p65 overexpression in luciferase assays. D, Co‐overexpression of NCOA6 and RELA/p65 did not synergistically enhance the increased reporter activity of the MMP9 promoter induced by RELA/p65 overexpression alone. All results are presented as the mean ± SD based on at least three independent experiments. **P < .01; the values with different letters are also significantly different (P < .05)