2-Demethoxy-2,3-ethylenediamino　hypocrellin　B　(EDAHB)　is　an　efficient　photosensitizer　that　mediates　cancer　cell　apoptosis.　In　order　to　better　understand　the　molecular　mechanisms　involved　in　its　antitumour　activity,　we　used　proteomics　technology　to　identify　candidate　targets　in　A549　cells　using　EDAHB-mediated　photodynamic　therapy　(EDAHB-PDT).　The　protein　profile　changes　between　untreated　and　PDT-treated　A549　cells　were　analysed　using　two-dimensional　polyacrylamide　gel　electrophoresis　(2-DE).　Differentially　expressed　protein　spots　were　identified　using　matrix-assisted　laser　desorption-time-of-flight　(MALDI-TOF)　mass　spectrometry;　and　15　differentially　expressed　proteins　(over　2-fold,　p＜0.05)　were　identified　in　PDT-treated　A549　cells　compared　with　untreated　cells.　Among　them,　the　expression　of　pyruvate　kinase　M2　(PKM2),　a　key　enzyme　involved　in　glycolysis,　was　found　to　be　significantly　decreased　in　A549　cells　following　EDAHB-PDT.　Transient　ectopic　over-expression　of　PKM2　attenuated　death　of　EDAHB-PDT-treated　A549　cells,　whereas　knockdown　of　PKM2　expression　by　RNA　interference　increased　the　photocytotoxicity　of　EDAHB.　Moreover,　a　decrease　in　lactate　production　was　detected　in　PDT-treated　A549　cells.　These　observations　suggest　that　PKM2　plays　an　important　role　in　the　antitumour　action　of　EDAHB-PDT;　thus,　it　may　be　a　potential　molecular　target　to　increase　the　efficacy　of　PDT　in　cancer　therapy.　(C)　2014　Elsevier　B.V.　All　rights　reserved.