Fig. 2.

CDK4 is highly expressed in human chondrosarcoma cell lines and CDK4 silencing decreases cell proliferation and suppresses the phosphorylation of Rb. (a) Human chondrosarcoma cell lines CS-1 and SW1353 were transfected with increasing concentrations of CDK4 specific siRNA or nonspecific siRNA for 3 days, and cell viability was determined by MTT assay after siRNA transfection. *P < 0.05, **P < 0.01 compared with control group. (b) The expression of respective proteins in CDK4/Rb-apoptosis signaling pathway was examined by western blotting. (c) Human chondrosarcoma cell lines CS-1 and SW1353 were transfected with 60 nM CDK4 specific siRNA or nonspecific siRNA or Control for 3 days, and expression of CDK4 in CS-1 and SW1353 was assessed by immunofluorescence with antibodies for CDK4 and Actin (scale bar =50 μm). Cells were visualized under a fluorescence microscope after incubation with secondary fluorescent conjugated antibodies Alexa Fluor 488 goat anti-rabbit IgG (green) or Alexa Fluor 594 goat anti-mouse IgG (red)