Effect of CYP2B1 siRNA on anti-Fx1A-induced gelsolin protein levels and effect of anti-Fx1A on gelsolin mRNA expression in GECs. The CYP2B1 was silenced in GECs infected with CYP2B1 adenovirus for 48 h. GECs were then treated with 4 mg/ml anti-Fx1A, followed by incubation with FHS or HIS. A negative siRNA (−ve siRNA) group was included to reflect the specificity of our silencing effect. A, the protein levels of gelsolin were determined by Western blotting. The blots are representative of three independent experiments. B, densitometry analysis of the Western blot result with gelsolin. The values represent net complement-mediated gelsolin protein decrease resulting from the loss of gelsolin protein by FHS minus the endogenous loss of gelsolin by HIS. Values are means ± S.E. (n = 3). *, p < 0.05 compared with the negative siRNA group. C, GECs were infected with CYP2B1 adenovirus, followed by treatment with anti-Fx1A (4 mg/ml) for 40 min at 22 °C, and incubated with FHS. A serum-free sample was used as a control. Gelsolin mRNA levels were determined by real-time RT-PCR. Values are means ± S.E. *, p < 0.05 compared with the control (Con).