When a gene expression profile for a limited gene group is desired, using a focused gene expression array is often more cost effective and more convenient than using a high-density microarray. siRNA is a powerful new research tool which can specifically turn off transcription of a target gene in vitro. Recently Perissi and colleagues used the combination of siRNA and a focused cDNA array to demonstrate the involvement of TBL1/TBLR1 in NFkB signaling pathway.

TBL1/TBLR1 are two F box/WD-40-containing factors that were originally identified as components of an N-CoR corepressor complex. In their study recently published on journal Cell, Perissi and colleagues reported that transcriptional activation mediated by liganded nuclear receptors unexpectedly requires the participation of both of these factors.

In one of their experiments, the author analyzed the requirement of TBL1/TBLR1 for NFkB transcriptional activation by using our NFkB signaling pathway GEArray containing 96 cDNA fragments. Using RNA samples extracted from 500 cells, the author showed that the activation of all the NFkB target genes induced by TNFa stimulation was lost when either TBL1 or TBLR1 was depleted by microinjection of synthesized gene specific siRNA into the cells.