ALA-PDT induces autophagic cell death in PC12 and CL1-0 cells. PC12 and CL1-0 cells were treated with 1 mM ALA for 3 hr, and then irradiated under the light dose of 2 and 12 J/cm2, respectively. (A) Autophagosome staining with MDC (upper panel) and expression pattern of transfected LC3-GFP (lower panel) after ALA-PDT in PC12 cells. In ALA-PDT treated cells, MDC (0.05 mM) accumulated as a punctate pattern (arrows) predominantly in the cytoplasm beginning as early as 2 hr post ALA-PDT. Photomicrographs of MDC staining cells were taken at 200× magnification. LC3-GFP (green), a known autophagosome marker, was expressed around the nuclear region. The nucleus was marked by Hoechst 33342 (blue). (B) Immunoblot analysis detected increased levels of the processed LC3-II in PC12 & CL1-0 cells treated with ALA-PDT, but not in cells treated with ALA only (control). β-actin was used as an internal control.