Tax⁺ mice develop osteolytic bone lesions and hypercalcemia of malignancy. (A) Between the ages of 4 and 12 months, Tax⁺ mice develop large granular leukemia/lymphoma tumors on the tails, legs, and ears (black arrows). Radiographic imaging demonstrates osteolytic bone destruction (white arrows) in the tail vertebra and the feet of a Tax⁺ mouse. (B) Dot plot of serum calcium (Ca²⁺) levels of tumor-bearing Tax⁺ mice (n = 19) and wild-type age-matched controls (n = 8). Tax⁺ mice had significantly higher serum Ca²⁺ (P < .01). (C) Tartrate-resistant acid phosphatase (TRAP) staining on decalcified tail vertebra of a representative Tax⁺ mouse. Hematoxylin-eosin staining shows tumor cells in the bone marrow, cortical bone, and subcutaneous tissue of a Tax⁺ mouse as indicated by arrows (top, × 20). TRAP stain of decalcified tail vertebra shows increased osteoclast recruitment at the marrow bone interface (bottom, × 20).