CN2-Cbi synergistically enhances sGC activation by NO-independent regulators, but not by nitric oxide. A, concentration-response curve to CN2-Cbi alone (□) or in combination with 0.5 (▴) or 5 μM (●) BAY41-2272. Data are means ± S.D. from four independent measurements performed in triplicate. B, concentration-response curve to BAY41-2272 alone (□) or in the presence of 25 (▴) or 100 μM (●) CN2-Cbi. Data are means ± S.D. of two independent measurements performed in triplicate. C, 20 μM CN2-Cbi synergistically enhances the stimulatory effect of submaximal concentration of heme-independent regulator HMR1766 (200 nM) and BAY58-2667 (20 nM). *, p < 0.05. D, concentration-response curve to DEA-NO alone (□) or in combination with 25 (●) or 100 (▴) μM CN2-Cbi. Data are means ± S.D. of two independent experiments performed in triplicate. *, p < 0.05, control versus CN2-Cbi; #, p < 0.05, 100 μM CN2-Cbi versus control.