Figure 5.

Cav-1-induced degradation of iNOS was mediated by the proteasome in detergent-insoluble fractions. Cells were stimulated for 15 h with cytokines before the addition of inhibitors for another 9 h. Degradation of iNOS protein was prevented by treatment of the cells with ALLN (10 μM) or lactacystin (lact.; 10 μM) but not E64D (50 μM) in both HT29 (A) and DLD1 (B) cells, independent of whether the parental, mock-, or cav-1-transfected (C13 or C4) cells were treated. (C) Mock- or cav-1-transfected (C13) HT29 cells were stimulated with cytokines, treated with ALLN, and fractionated on sucrose gradients as described.