EGFR and neoplasm: To determine if tumor penetration, EGFR saturation, and inhibition of EGFR activation and proliferation correlated with anti-tumor activity, mice bearing A431 xenograft tumors of approximately 300 mm3 tumors were injected intraperitoneally twice a week for 50 days with PBS, 500 μg of control IgG2 antibody, or 5, 20, 200 or 500 μg of panitumumab (n = 10 animals in each treatment group).