I am looking at a plant promoter with 4 W-boxes nearly adjacent to one another. Individual mutation of the W-boxes weakly suppressed gene expression for 3 of the 4 W-boxes, but for 1 of them, it actually enhanced gene expression substantially. The hypothesis is that that one W-box normally binds a repressor and that the other 3 may bind enhancers. The question is, could those 3 W-boxes possibly be redundant/synergistic and might they counter the effect of the 4th to ensure tight transcriptional regulation? I am looking for other published examples of this possibility.