Objective To investigate whether TG2 plays an important role in the osteoblast differentiation and mineralization. Methods TG2 mRNA of SaOS-2 cells was knocked down using a lentivirus stably expressing short-hairpin(sh) RNA targeting TG2.Then the cells were cultured in osteo-inductive medium for 14 d to measure mineralization and for 7 d to measure the levels of osteoblastic differentiation markers including ALP activity and mRNA of collagen I, osteocalcin(OCN) and BMP-2.The wild-type SaOS-2 cells and scrambled shRNA-transducted SaOS-2 cells served as the controls. Results The controls displayed an increasing trend of the level of ALP activity and mRNA of collagen I, osteocalcin and BMP-2,and notable mineralization at 14 d.When TG2 was knocked down, ALP activity, mRNA of collagen I, osteocalcin and BMP-2 at 7d,and mineralization at 14 d were all significantly lower in comparison with the corresponding values in the controls.Conclusion TG2 is involved in the differentiation and mineralization of osteoblasts in vitro.