Robustness of the microchamber array was demonstrated by coculture and primary cell experiments. (A) Effect of HS-5s on STAT3 activation. Phalloidin (red) and Hoechst (blue) stains showed compartmentalization of cell types in their respective chambers. Scale bar represents 1 mm (inset scale bar represents 500 μm). Hoechst (blue) and STAT3 (green) stains showed marked increase in nuclear STAT3 for cocultured RPMI 8226 cells compared with monoculture. Histograms of IR values (x-axis) for monoculture (red) versus coculture (blue), where y-axis is relative frequency (R.F.). Population mean IR for coculture was normalized to the population mean IR for monoculture (IR fold increase in bar graph, n = 3; independent averages of quadruplicates). Error bars represent SE. (B) CLL primary patient sample showed detectable NF-κB activation by BAFF and lipopolysaccharide. Shape of distribution differed from cocultured RPMI 8226 distribution in panel A. Scale bar represents 20 μm; graph, n = 1. ○ represents triplicates; and bar, triplicate average. (C) List of experimental conditions tested.