To investigate the effect of miR-133b over-expression on the expression of target genes in osteosarcoma cells, as well as to study the molecular mechanism how miR-133b influences the phenotype of osteosarcoma cell, we measured the expression of BCL2L2, MCL-1, IGF1R, MET, phospho-Akt, PTEN and FAK using Western blotting. The gene discussed is MCL1; the disease is osteosarcoma.