Reduced tumor burden in src^–/– mice following experimental lung metastasis. Syngeneic D121 lung carcinoma cells were injected intravenously in the tail vein of src^–/– and control src^+/– mice, and lung tumor burden determined after 13 to 15 days, as described in “Materials and methods.” (A) Wet lung weights of D121 tumors from src^–/– and src^+/– are shown (*P < .036; n = 6). Error bars indicate standard error. (B) Representative stereomicrographs of lung tumor burden are shown from src^–/– or control src^+/– hosts.