In addition, RUNX2 expressed from the P2 promoter regulates hypertrophy and proliferation of both chondrocytes and the closely-related immature osteoblasts. The human osteosarcoma cell line SAOS-2 has persistently high RUNX2 protein levels, driven by the P2 promoter. Hence, preferential expression of RUNX2 from the ��early-activated�� P2 promoter rather than the ��late-activated�� P1 promoter in osteosarcomas suggests that osteosarcomas may originate from immature mesenchymal progenitor cells. The samples in this study consisted of tumor resections both from patients who had been treated with chemotherapy and from pre-chemotherapeutic biopsies. Statistically significant gene expression differences between resections and Mazindol biopsies existed for the expression levels of CDKN1A, MDM2, BCL2L1, PTEN, and WWOX. CDKN1A is activated in response to activation of the ATM/TP53 DNA damage checkpoint that accommodates double-stranded DNA repair and inhibits cell cycle progression by CDK4, MDM2 is an inhibitor of TP53, BCL2L1 is an anti-apoptotic factor, PTEN is a tumor suppressor commonly lost in osteosarcomas, and WWOX is a tumor suppressor that inhibits RUNX2 activity. Furthermore, all of these genes encode proteins important for cell cycle regulation. The IPA analysis of the data confirms significant relationships between proteins in theTP53-RB1-centred network of protein interactions that also involve PI3K, PTEN/Akt, MYC, and RECQL4. All of the aforementioned genes were more highly expressed in the resections. Our results are consistent with experiments in osteosarcoma cell lines that have shown that drug treatment induces growth arrest and increases levels of CDKN1A, MDM2, and BCL2L1. (+)-Norfenfluramine hydrochloride Galectins constitute a family of lectins defined by shared consensus amino acid sequences and affinity for b-galactosecontaining oligosaccharides. In mammals, the distribution of galectins is tissue-specific and their expression is developmentally regulated. They play an important role in several physiological processes, including embryonic development, wound healing, apoptosis, intercellular adhesion, cell migration, and immune response.