PinX1 suppress MMP-9 expression via NF-κB-dependent transcription. (A) and (B) Western blot analysis of the relative protein levels of PinX1, MMP-9 and NF-κB-p65 in four groups of control, PinX1OE , PinX1KD and PinX1KD co-treated with NF-κB-p65 siRNA for both MDA-MB-231 and BT-549 stable cell lines. The NF-κB specific siRNA dramatically prevented the up-regulation of MMP-9 expression induced by PinX1 knockdown. (C) and (D) The increased ability of migration and invasion regulated by PinX1 knockdown was suppressed by NF-κB-p65 siRNA in both MDA-MB-231 and BT-549 stable cell lines. All experiments were carried out in triplicate. Histograms represent means ± SD. ***, P < 0.001.