Figure 5.

Phosphorylation of MKP1 is not required for MG132 stabilization. A, Fourteen-day-old transgenic seedlings were treated with or without 40 µm MG132 for 1 h. Protein extracts from treated seedlings were separated with 8% mini-format (8.3 × 7.3 cm) SDS-PAGE and immunoblotting with anti-myc antibody to detect the myc-MKP1 protein (top) and anti-MPK6 antibody as a loading control (bottom). LE, Long exposure; SE, short exposure. B and C, Quantification of the western-blot band intensity of MKP1 protein, which was normalized to that of MKP6 as a loading control. Graphed are means ± se, pooling from three independent biological replicates (n = 3). The asterisks indicate significant differences between pairwise groups (marked by parentheses: *, P < 0.05 and **, P < 0.01). The statistical test was performed using ANOVA with multiple pairwise comparisons under the protection of an overall F test.