Inhibition of C5a-induced CAT activity by IκBM. RAW264.7 cells were cotransfected with the dominant negative IκBM plasmid (4 μg; lane 4) and the p-272CAT reporter plasmid, using transfection conditions described above and in Materials and Methods. After serum starvation, the cells were either unstimulated (lane 1) or stimulated with TNF (40 ng/mL, lane 1) or C5a (100 nmol/L, lanes 3 and 4) for 4 hours before the assay.