Aromatase Inhibitor Letrozole Xenografts and Cells during Prolonged Treatment with Activation of Mitogen-Activated Protein Kinase in


Ovariectomized mice bearing tumor xenografts grown from aromatase-transfected estrogen receptor (ER)–positive human breast cancer cells (MCF-7Ca) were injected s.c. with 10 Mg/d letrozole for up to 56 weeks. Western blot analysis of the tumors revealed that ERs (ERA) were increased at 4 weeks but decreased at weeks 28 and 56. Expression of erbB-2 and p-Shc… (More)


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