Protection against pulmonary metastases. BALB/c mice (4T1 tumor model) were treated i.v. once a week for 6 weeks with 20 μg LDC beginning 4 days after subcutaneous challenge with 8 × 105 4T1 tumor cells. Top(A): representative lung metastatic nodule specimens from mice challenged with 4T1 breast tumor cells; bottom(B): average numbers of lung metastatic nodules. The lungs from pORF-hFlk-1-treated mice showed significant differences compared with other groups (P < 0.05 or P < 0.01). Columns: mean lung metastatic nodules (n = 5); bars: SD.