(A) Bioluminescence images of representative mice in bombesin (BBN)-treated and control mice with subcutaneous Ace-1- huGRPr tumors at different time points (1, 7, 14, and 21 day). (B) Representative histopathology of Ace-1-huGRPr tumors from bombesin (BBN)-treated and control mice. Neoplastic cells were epithelioid and polyhedral in control mice (left panel; arrowheads) and spindle-shaped in the bombesin-treated mice (right panel, arrowheads). (C) Histopathology of subcutaneous tumors in bombesin-treated mice showing infiltration of neoplastic cells into adipose (left) and muscle (right) tissues (arrowheads). (D) Histopathology of tibias from bombesin-treated and control mice that were injected with Ace-1-huGRPr cells. Note intramedullary tumors with osteoclastic bone resorption in a bombesin-treated mouse (upper panel, arrowheads) and osteoblastic new bone formation in a control mouse (lower panel, arrowheads). (E) Radiographic images of intratibial Ace-1-huGRPr tumors from a bombesin-treated mouse (upper panel) and a control mouse (lower panel) revealing radiolucent osteolytic foci in the tibia of BBN-treated mouse (arrowhead) and a radiodense osteoblastic tumor in the tibia of a control mouse (arrowhead).