Figure 5.

TM promotes degradation of nonglycosylated EGFR. A, B. HN4 and CAL27 cells were treated with or without TM for 2 hours and then incubated with cycloheximide (CHX; 10 μM) for an extended period of time. The levels of EGFR were determined by western blot analysis. C, D. Graphic representation of the densitometry results of EGFR after cycloheximide (CHX) treatment (circle, glycosylated EGFR with DMSO; square, glycosylated EGFR with TM; triangle, nonglycosylated EGFR with TM). E. Inhibition of EGFR glycosylation enhances ubiquitination. CAL27 cells treated with TM and/or MG132 were subjected to EGFR immunoprecipitation (IP) and western blot analyses with anti-ubiquitin.