Effect of isoimperatorin treatment on the viability of rabbit articular chondrocytes. Chondrocytes were treated with the indicated concentrations (0.0–737.74 μM) of isoimperatorin for 24 h. Photographs of chondrocytes (A) were taken with a phase-contrast microscope (200× magnification). Cell viability was estimated using the methyl thiazole tetrazolium (MTT) assay. The graphical data (B) are expressed as mean ± standard error of mean.