12. Usuda J, Tsunoda Y, Ichinose S, Ishizumi T, Ohtani K, et al. (2010) Breast cancer resistant protein (BCRP) is a molecular determinant of the outcome of photodynamic therapy (PDT) for centrally located early lung cancer. Lung Cancer 67: 198–204. 13. Kobayashi W, Liu Q, Nakagawa H, Sakaki H, Teh B, et al. (2006) Photodynamic therapy with mono-l-aspartyl chlorin e6 can cause necrosis of squamous cell carcinoma of tongue: Experimental study on an animal model of nude mouse. Oral oncology 42: 45–49. 14. Agostinis P, Buytaert E, Breyssens H, Hendrickx N (2004) Regulatory pathways in photodynamic therapy induced apoptosis. Photochem Photobiol Sci 3: 721–729. 15. Josefsen LB, Boyle RW (2008) Photodynamic therapy: novel third-generation photosensitizers one step closer? Br J Pharmacol 154: 1–3. 16. Allaker RP, Douglas CW (2009) Novel anti-microbial therapies for dental plaque-related diseases. Int J Antimicrob Agents 33: 8–13. 17. Wood S, Metcalf D, Devine D, Robinson C (2006) Erythrosine is a potential photosensitizer for the photodynamic therapy of oral plaque biofilms. J Antimicrob Chemother 57: 680–684. 18. Gandin E, Lion Y, Van de Vorst A (1979) Production of radicals by singlet oxygen reaction: an E.S.R. study [proceedings]. Arch Int Physiol Biochim 87: 1046–1047. 19. Allison RR, Downie GH, Cuenca R, Hu X-H, Childs CJH, et al. (2004) Photosensitizers in clinical PDT. Photodiagnosis and Photodynamic Therapy 1: 27–42. 20. Nagel W, Somieski P, Katz U (2001) Selective inhibition of Cl(2) conductance in toad skin by blockers of Cl(2) channels and transporters. Am J Physiol Cell Physiol 281: C1223–1232. 21. Plaetzer K, Kiesslich T, Verwanger T, Krammer B (2003) The Modes of Cell Death Induced by PDT: An Overview. Med Laser Appl 18: 7–19. 22. He YY, Council SE, Feng L, Bonini MG, Chignell CF (2008) Spatial distribution of protein damage by singlet oxygen in keratinocytes. Photochem Photobiol 84: 69–74. 23. Moan J, Berg K (1991) The photodegradation of porphyrins in cells can be used to estimate the lifetime of singlet oxygen. Photochem Photobiol 53: 549–553. 24. Moor ACE, Ortel B, Hasan T (2003) Mechanisms of photodynamic therapy. In: Patrice T, ed. Photodynamic Therapy. Cambridge: The Royal Society of Chemistry. pp 19–57. 25. Buytaert E, Dewaele M, Agostinis P (2007) Molecular effectors of multiple cell death pathways initiated by photodynamic therapy. Biochim Biophys Acta 1776: 86–107. 26. Garg AD, Nowis D, Golab J, Vandenabeele P, Krysko DV, et al. (2010) Immunogenic cell death, DAMPs and anticancer therapeutics: an emerging amalgamation. Biochim Biophys Acta 1805: 53–71. 27. Hengartner MO (2000) The biochemistry of apoptosis. Nature 407: 770–776. 28. Green DR, Reed JC (1998) Mitochondria and apoptosis. Science 281: 1309–1312. 29. Bolte S, Cordelieres FP (2006) A guided tour into subcellular colocalization analysis in light microscopy. J Microsc 224: 213–232. 30. Moan J, Peng Q (2003) An outline of the history of PDT. In: Patrice T, ed. Photodynamic Therapy. Cambridge: The Royal Society of Chemistry. pp 1–18. 31. Alberts B, Johnson A, Lewis J, Raff M, Roberts K, et al. (2002) Molecular Biology of the Cell. New York: Garland Science Publications. Erythrosine-Based PDT of Oral Epithelial Cells 32. Sharman WM, van Lier JE, Allen CM (2004) Targeted photodynamic therapy via receptor mediated delivery systems. Adv Drug Deliv Rev 56: 53–76. 33. Siboni G, Weitman H, Freeman D, Mazur Y, Malik Z, et al. (2002) The correlation between hydrophilicity of hypericins and helianthrone: internaliza- tion mechanisms, subcellular distribution and photodynamic action in colon carcinoma cells. Photochem Photobiol Sci 1: 483–491. 34. Vazifeh D, Bryskier A, Labro MT (1999) Mechanism underlying levofloxacin uptake by human polymorphonuclear neutrophils. Antimicrob Agents Che- mother 43: 246–252. 35. Friberg EG, Cunderlikova B, Pettersen EO, Moan J (2003) pH effects on the cellular uptake of four photosensitizing drugs evaluated for use in photodynamic therapy of cancer. Cancer Lett 195: 73–80. 36. Geserick C, Blasco MA (2006) Novel roles for telomerase in aging. Mechanisms of Ageing and Development 127: 579–583. 37. Loebinger MR, Sage EK, Davies D, Janes SM (2010) TRAIL-expressing mesenchymal stem cells kill the putative cancer stem cell population. Br J Cancer 103: 1692–1697. 38. Indran IR, Hande MP, Pervaiz S (2011) hTERT Overexpression Alleviates Intracellular ROS Production, Improves Mitochondrial Function, and Inhibits ROS-Mediated Apoptosis in Cancer Cells. Cancer Research 71: 266–276. 39. Gottesman MM (2002) Mechanisms of cancer drug resistance. Annu Rev Med 53: 615–627. 40. Schuler M, Bossy-Wetzel E, Goldstein JC, Fitzgerald P, Green DR (2000) p53 Induces Apoptosis by Caspase Activation through Mitochondrial Cytochrome c Release. Journal of Biological Chemistry 275: 7337–7342. 41. Chaloupka R, Petit PX, Israe¨l N, Sureau F (1999) Over-expression of Bcl-2 does not protect cells from hypericin photo-induced mitochondrial membrane depolarization, but delays subsequent events in the apoptotic pathway. FEBS Letters 462: 295–301. 42. Chiu SM, Oleinick NL (2001) Dissociation of mitochondrial depolarization from cytochrome c release during apoptosis induced by photodynamic therapy. Br J Cancer 84: 1099–1106. 43. Kim R, Emi M, Tanabe K, Murakami S, Uchida Y, et al. (2006) Regulation and interplay of apoptotic and non-apoptotic cell death. The Journal of Pathology 208: 319–326. 44. Castano AP, Demidova TN, Hamblin MR (2005) Mechanisms in photodynamic therapy: part two–cellular signaling, cell metabolism and modes of cell death. Photodiagnosis and Photodynamic Therapy 2: 1–23. 45. Luo Y, Kessel D (1997) Initiation of Apoptosis versus Necrosis by Photodynamic Therapy with Chloroaluminum Phthalocyanine. Photochemistry and Photobi- ology 66: 479–483. 46. Shah GM, Shah RG, Poirier GG (1996) Different Cleavage Pattern for Poly(ADP-Ribose) Polymerase during Necrosis and Apoptosis in HL-60 Cells. Biochemical and Biophysical Research Communications 229: 838–844. 47. Chang SE, Foster S, Betts D, Marnock WE (1992) DOK, a cell line established from human dysplastic oral mucosa, shows a partially transformed non- malignant phenotype. International Journal of Cancer 52: 896–902. 48. Prime SS, Matthews JB, Patel V, Game SM, Donnelly M, et al. (1994) TGF-b receptor regulation mediates the response to exogenous ligand but is independent of the degree of cellular differentiation in human oral keratinocytes. International Journal of Cancer 56: 406–412. PLoS ONE | www.plosone.org 12 April 2012 | Volume 7 | Issue 4 | e34475