Figure 3.

Insulin-induced EGFR phosphorylation depends on MMP activity. Serum- and growth-factor-starved THCE cells were treated with 50 μM GM6001 (A), 10 μg/ml CRM197 (B), 10 μM DPI (C), or DMSO for 1 h and further incubated with or without 5 μg/ml insulin for 10 min. Cell lysates were immunoprecipitated with EGFR antibody, subjected to SDS-PAGE, and probed with phosphotyrosine (PY20H) antibody. To assess phosphorylation of ERK, samples of the lysates were immunoblotted with phospho-ERK1/2 antibody. ERK1/2 antibody was used as a probe to normalize protein loading. The results are representative of three independent experiments.