I. To determine the levels of RING ubiquitin ligases mRNA and protein in differentiating human mesenchymal precursor cells: To test the correlation between levels of RING ubiquitin ligases and degree of osteogenic differentiation, we will extract mesenchymal precursor cells from the collected tissue and test the mRNA protein level of RING ubiquitin ligases upon induction of differentiation. Specifically, we will compare the levels of RING ubiquitin ligases before and after the initiation of differentiational stimulus in time dependent manner by western blot and real time PCR analysis.