(A) In vivo imaging of fluorescent tumor area to monitor tumor growth. Nude mice were injected with 1 x 105 MDA-231BO-DsRed2 cells into the left ventricle and fluorescent imaging was performed at regular intervals. Analyses of fluorescent tumor area was performed for Control (n = 7), Sunitinib (n = 7). Box plot shows 25–75 percentiles, whiskers 05–95 percentiles, + indicates mean and line indicates median. Significance was determined by 2-tailed Student t-test (*p < 0.05). Growth inhibition with Sunitinib treatment is significantly reduced at 4 and 5 weeks following tumor cell inoculation (mean ± SD: Week 4. Ctrl 8.62 ± 5.13; Sunitinib 4.99 ±3.00. Week 5. Ctrl 14.75 ± 4.97; Sunitinib 9.30 ± 5.42). (B) Histomorphometric determination of cross-sectional tumor size. Longitudinal sections of distal femur were stained with Goldners trichrome and the tumor area measured from the epiphyseal line associated with the growth plate and extending into the diaphysis and bilaterally between the endocortical envelope. The tumor margin measured is marked by a green line. At regions of extensive cortical destruction, the line was drawn to the boundary of the periosteum. Representative sections of Goldner’s trichrome stained femur from control and Sunitinib treated mice are shown. Magnification 5x (C) Cross-sectional tumor size in bone as measured by histomorphometry is significantly decreased with Sunitinib treatment (Control mean ± SD 2.19 ± 0.39, n = 5; Sunitinib mean ± SD 1.59 ± 0.43; n = 5, p < 0.05).