Lack of BMPER in A549 carcinoma cells modulates expression of MMPs and expression of the BMP target gene Id1. (a, b and d) mRNA expression of MMP-2, MMP-9 and Id1 in A549 cells after 24, 48 and 72 h post transfection with siRNA BMPER I or II was analyzed compared with scrambled siRNA control. mRNA content was quantified by real-time (q)PCR using specific primers for MMP-2, MMP-9, Id1 and hRP as internal control. Knock-down efficiency was calculated using ΔΔCT method. Mean±s.d.; *P<0.05 versus control. (c) Representative gelatin zymography assay of conditioned media collected from siRNA-transfected A549 cells 72 h post transfection. MMPs degrade gelatin and produce a white band in the coomassie-stained gelatin SDS gel. (e) Western blot analysis for Id1 was performed 48 h post transfection. GAPDH served as loading control. Densitometric analysis of Id protein expression for three independent experiments is shown. Mean±s.d.; *P<0.01 versus control.