Earthworm extract enhances the proliferation of osteoblasts. MG-63 cells were cultured with PBS as a control or different concentrations of earthworm extract. Osteoblast viability was measured by MTT assay after 2 day of culture. (*p < 0.05, **p < 0.01 and ***p < 0.001 vs. control; #
p < 0.05 and ###
p < 0.001 vs. 3 mg/ml).