When epidermal growth factor (EGF)—the ligand for the epidermal growth factor receptor (EGFR)—binds EGFR on the cell surface, the intracellular domain of the receptor changes shape into an "active state.” The receptor then induces a cascade of kinases in the cytoplasm, resulting in the activation of mitogen-activated protein kinase (MAPK). One effect of EGFR signaling is the stimulation of cell proliferation. Overactive EGFR is frequently found in cancer cells. One strategy for developing anticancer drugs is to target the overactive signaling proteins found in cancer cells. Antibodies are proteins made by immune cells that only recognize specific biomolecules, called antigens. The major component of an anticancer drug is an antibody that specifically recognizes and binds EGFR.

Which of the following will most likely happen when this anticancer drug is applied to a tumor that has a high level of EGFR?

A. Tumor cells with active EGFR will increase and MAPK activity in the tumor will increase.
B. Tumor cells with active EGFR will decrease and MAPK activity in the tumor will increase.
C. Tumor cells with active EGFR will increase and MAPK activity in the tumor will decrease.
D. Tumor cells with active EGFR will decrease and MAPK activity in the tumor will decrease.