Figure 1: Inhibition of the cell growth and induction of apoptosis by PK in human malignant glioma cell SHG-44. After treating with different concentration of PK for 48 h, the cells were observed using an inverted microscope (Zeiss Axio Observer A1) or stained with Hoechst 33258, and then photographed with a fluorescence microscope. Compared to the control cells, cells exposed to PK presented typical apoptotic morphology with cell shrinkage, nuclear condensation, and formation of apoptotic bodies, with rupture of cells. The Hoechst 33258 dye stained morphologically normal nuclei dimly blue, whereas PK-treated cells demonstrated smaller nuclei with brilliant blue staining (arrows indicate condensed nuclei).