Induction of differentiation and apoptosis by decitabine treatment of U2OS in vivo. A), Decitabine effects on tumor volumes in vivo. The results compare tumor volumes in control xenografts to decitabine treated xenografts as described in methods. Each column is the Mean of tumor volumes measured in 12 xenograft tumors. There was a significant decrease (p < 0.05) in tumor volumes as a result of decitabine treatment. B), Osteoid assessment in vivo. Each column is the Mean of osteoid evaluation of 9 sections. There was significant increase (p < 0.0001) in osteoid formation as a result of decitabine treatment. C), Representation images of H&E sections. Control xenograft tumors (left) show solid sheets of poorly differentiated cells with minimal osteoid (image magnification × 100). Decitabine treated tumors shows less dense cell population and increased areas of osteoid seen as light pink and lacy matrix with the nuclei of osteoblasts sitting closer to the produced matrix (image magnification × 100). The arrows in the enlargement show the osteoid matrix surrounding osteoblasts (defined as eosinophilic osteoid-like material). C), And D), Mitotic count as identified in the same sections used to asses for osteoid evaluation. Each column is the Mean mitotic count in 9 sections (a minimum of 1100 nuclei were scanned per section). Decitabine treatment resulted in a significantly lower mitotic count (p < 0.0001). The arrows in the enlargement image in C (left) indicate mitotic nuclei. E), Results for apoptosis analysis by TUNEL assay. Each column is the Mean count of TUNEL positive nuclei seen in 9 images representing 9 sections (≥1000 nuclei were scanned per section). There was a significant increase (p < 0.05) of apoptotic cells as a result of decitabine treatment. F), Representation images from TUNEL assay of control tumors (left) and decitabine treated tumors  (image magnification × 200). The arrows in the enlargement image show the TUNEL-positive nuclei (apoptotic nuclei). Error bars indicate standard deviation from the Mean values and p-values are based on comparison between control and decitabine treated tumors using student t-test.