Independent of primary tumor size, metastases formation is accelerated in MKR+/+ mice. A total of 100,000 Mvt1 cells were injected into the inguinal mammary fat pad of 8- to 10-week-old mice (8 to 10 mice per group). Developing tumors were removed surgically when they reached a specific size (30 to 40 mm3). (A) Volumes and (B) weights of tumors from MKR+/+ and control mice at time of surgical removal. (C) Number of metastases present in the lungs of control and MKR+/+ mice four weeks after tumor resection. (D) Number of metastases present in the lungs of control and MKR+/+ mice three weeks after intravenous injection of 10,000 Mvt1 cells. Error bars represent SEM, **, P ≤ 0.05.