(A-B) Immunofluorescence staining of Ki67 (A) and percent Ki67-positive cells (B) in 4T1 tumor tissues harvested on day 12 from mice treated with vehicle (control), zoledronic acid (ZA), docetaxel (DTX), or ZA plus DTX. (C-E) Photographs of India ink-filled lungs (C), counted average of tumor metastatic lesions in the lungs (D), and the H&E staining of lung slices (E) from 4T1 tumor-bearing mice (on day 12) treated with vehicle (control), ZA, DTX, or ZA plus DTX. Tumor metastases appear as white nodules on the black lung surfaces and are indicated by red arrows. Tumor metastases in the H&E stained lung slices are indicated by the dashed circles. *, P <0.05; ***, P <0.001.