4168 Nucleic Acids Research, 2008, Vol. 36, No. 12 21. Dorsett,Y. and Tuschl,T. (2004) siRNAs: applications in functional genomics and potential as therapeutics. Nat. Rev. Drug Discov., 3, 318–329. 22. Carette,J.E., Overmeer,R.M., Schagen,F.H., Alemany,R., Barski,O.A., Gerritsen,W.R. and Van Beusechem,V.W. (2004) Conditionally replicating adenoviruses expressing short hairpin RNAs silence the expression of a target gene in cancer cells. Cancer Res., 64, 2663–2667. 23. Grimm,D., Streetz,K.L., Jopling,C.L., Storm,T.A., Pandey,K., Davis,C.R., Marion,P., Salazar,F. and Kay,M.A. (2006) Fatality in mice due to oversaturation of cellular microRNA/short hairpin RNA pathways. Nature, 441, 537–541. 24. Xu,D., McCarty,D., Fernandes,A., Fisher,M., Samulski,R.J. and Juliano,R.L. (2005) Delivery of MDR1 small interfering RNA by self-complementary recombinant adeno-associated virus vector. Mol. Ther., 11, 523–530. 25. Sazani,P. and Kole,R. (2003) Therapeutic potential of antisense oligonucleotides as modulators of alternative splicing. J. Clin. Invest., 112, 481–486. 26. Valencia-Sanchez,M.A., Liu,J., Hannon,G.J. and Parker,R. (2006) Control of translation and mRNA degradation by miRNAs and siRNAs. Genes Dev., 20, 515–524. 27. Hannon,G.J. (2002) RNA interference. Nature, 418, 244–251. 28. Paddison,P.J. and Hannon,G.J. (2002) RNA interference: the new somatic cell genetics? Cancer Cell, 2, 17–23. 29. Hammond,S.M. (2005) Dicing and slicing: the core machinery of the RNA interference pathway. FEBS Lett., 579, 5822–5829. 30. Ameres,S.L., Martinez,J. and Schroeder,R. (2007) Molecular basis for target RNA recognition and cleavage by human RISC. Cell, 130, 101–112. 31. Eulalio,A., Behm-Ansmant,I. and Izaurralde,E. (2007) P bodies: at the crossroads of post-transcriptional pathways. Nat. Rev. Mol. Cell Biol., 8, 9–22. 32. Buhler,M. and Moazed,D. (2007) Transcription and RNAi in heterochromatic gene silencing. Nat. Struct. Mol. Biol., 14, 1041–1048. 33. Czech,M.P. (2006) MicroRNAs as therapeutic targets. N. Engl. J. Med., 354, 1194–1195. 34. Krutzfeldt,J., Kuwajima,S., Braich,R., Rajeev,K.G., Pena,J., Tuschl,T., Manoharan,M. and Stoﬀel,M. (2007) Speciﬁcity, duplex degradation and subcellular localization of antagomirs. Nucleic Acids Res., 35, 2885–2892. 35. Krutzfeldt,J., Rajewsky,N., Braich,R., Rajeev,K.G., Tuschl,T., Manoharan,M. and Stoﬀel,M. (2005) Silencing of microRNAs in vivo with ‘antagomirs’. Nature, 438, 685–689. 36. Elbashir,S.M., Harborth,J., Lendeckel,W., Yalcin,A., Weber,K. and Tuschl,T. (2001) Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells. Nature, 411, 494–498. 37. Corey,D.R. (2007) RNA learns from antisense. Nat. Chem. Biol., 3, 8–11. 38. De Paula,D., Bentley,M.V. and Mahato,R.I. (2007) Hydrophobization and bioconjugation for enhanced siRNA delivery and targeting. RNA, 13, 431–456. 39. Fisher,M., Abramov,M., Van Aerschot,A., Xu,D., Juliano,R.L. and Herdewijn,P. (2007) Inhibition of MDR1 expression with altritol- modiﬁed siRNAs. Nucleic Acids Res., 35, 1064–1074. 40. Manoharan,M. (2004) RNA interference and chemically modiﬁed small interfering RNAs. Curr. Opin. Chem. Biol., 8, 570–579. 41. Corey,D.R. (2007) Chemical modiﬁcation: the key to clinical application of RNA interference? J. Clin. Invest., 117, 3615–3622. 42. Reynolds,A., Leake,D., Boese,Q., Scaringe,S., Marshall,W.S. and Khvorova,A. (2004) Rational siRNA design for RNA interference. Nat. Biotechnol., 22, 326–330. 43. Kleinman,M.E., Yamada,K., Takeda,A., Chandrasekaran,V., Nozaki,M., Baﬃ,J.Z., Albuquerque,R.J., Yamasaki,S., Itaya,M., Pan,Y. et al. (2008) Sequence- and target-independent angiogenesis suppression by siRNA via TLR3. Nature, 452, 591–597. 44. Kirkham,M. and Parton,R.G. (2005) Clathrin-independent endo- cytosis: new insights into caveolae and non-caveolar lipid raft carriers. Biochim. Biophys. Acta, 1745, 273–286. 45. Perret,E., Lakkaraju,A., Deborde,S., Schreiner,R. and Rodriguez- Boulan,E. (2005) Evolving endosomes: how many varieties and why? Curr. Opin. Cell Biol., 17, 423–434. 46. Echarri,A., Muriel,O. and Del Pozo,M.A. (2007) Intracellular traﬃcking of raft/caveolae domains: insights from integrin signal- ing. Semin. Cell Dev. Biol., 18, 627–637. 47. Parton,R.G. and Simons,K. (2007) The multiple faces of caveolae. Nat. Rev. Mol. Cell Biol, 8, 185–194. 48. Pfeﬀer,S.R. (2007) Unsolved mysteries in membrane traﬃc. Annu. Rev. Biochem., 76, 629–645. 49. Cai,H., Reinisch,K. and Ferro-Novick,S. (2007) Coats, tethers, Rabs, and SNAREs work together to mediate the intracellular destination of a transport vesicle. Dev. Cell, 12, 671–682. 50. van der Goot,F.G. and Gruenberg,J. (2006) Intra-endosomal membrane traﬃc. Trends Cell Biol., 16, 514–521. 51. Grosshans,B., Ortiz,D. and Novick,P. (2006) Rabs and their eﬀectors: achieving speciﬁcity in membrane traﬃc. Proc. Natl Acad. Sci. USA, 103, 11821–11827. 52. Carlton,J., Bujny,M., Rutherford,A. and Cullen,P. (2005) Sorting nexins—unifying trends and new perspectives. Traﬃc, 6, 75–82. 53. Di Guglielmo,G.M., Le Roy,C., Goodfellow,A.F. and Wrana,J.L. (2003) Distinct endocytic pathways regulate TGF-beta receptor signalling and turnover. Nat. Cell Biol., 5, 410–421. 54. Chen,H. and De Camilli,P. (2005) The association of epsin with ubiquitinated cargo along the endocytic pathway is negatively regulated by its interaction with clathrin. Proc. Natl Acad. Sci. USA, 102, 2766–2771. 55. Subtil,A., Gaidarov,I., Kobylarz,K., Lampson,M.A., Keen,J.H. and McGraw,T.E. (1999) Acute cholesterol depletion inhibits clathrin- coated pit budding. Proc. Natl Acad. Sci. USA, 96, 6775–6780. 56. Pelkmans,L., Puntener,D. and Helenius,A. (2002) Local actin polymerization and dynamin recruitment in SV40-induced inter- nalization of caveolae. Science, 296, 535–539. 57. Aplin,A.E. and Juliano,R.L. (1999) Integrin and cytoskeletal regulation of growth factor signaling to the MAP kinase pathway. J. Cell Sci., 112(Pt 5), 695–706. 58. Marbet,P., Rahner,C., Stieger,B. and Landmann,L. (2006) Quantitative microscopy reveals 3D organization and kinetics of endocytosis in rat hepatocytes. Microsc. Res. Tech., 69, 693–707. 59. Zerial,M. and McBride,H. (2001) Rab proteins as membrane organizers. Nat. Rev. Mol. Cell Biol., 2, 107–117. 60. Juliano,R.L., Alahari,S., Yoo,H., Kole,R. and Cho,M. (1999) Antisense pharmacodynamics: critical issues in the transport and delivery of antisense oligonucleotides. Pharm. Res., 16, 494–502. 61. Wang,L., Prakash,R.K., Stein,C.A., Koehn,R.K. and Ruﬀner,D.E. (2003) Progress in the delivery of therapeutic oligonucleotides: organ/cellular distribution and targeted delivery of oligonucleotides in vivo. Antisense Nucleic Acid Drug Dev., 13, 169–189. 62. Alam,M.R., Dixit,V., Kang,H., Li,Z.-B., Chen,X., Trejo,J., Fisher,M. and Juliano,R.L. (2008) Intracellular delivery of an anionic antisense oligonucleotide via receptor mediated endocytosis. Nucleic Acids Res., 36, 2764–2776. 63. El-Andaloussi,S., Johansson,H.J., Holm,T. and Langel,U. (2007) A novel cell-penetrating peptide, M918, for eﬃcient delivery of proteins and peptide nucleic acids. Mol. Ther., 15, 1820–1826. 64. Overhoﬀ,M. and Sczakiel,G. (2005) Phosphorothioate-stimulated uptake of short interfering RNA by human cells. EMBO Rep., 6, 1176–1181. 65. Dietz,G.P. and Bahr,M. (2004) Delivery of bioactive molecules into the cell: the Trojan horse approach. Mol. Cell Neurosci., 27, 85–131. 66. Patel,L.N., Zaro,J.L. and Shen,W.C. (2007) Cell penetrating peptides: intracellular pathways and pharmaceutical perspectives. Pharm. Res., 24, 1977–1992. 67. Gupta,B., Levchenko,T.S. and Torchilin,V.P. (2005) Intracellular delivery of large molecules and small particles by cell-penetrating proteins and peptides. Adv. Drug Deliv. Rev., 57, 637–651. 68. Howl,J., Nicholl,I.D. and Jones,S. (2007) The many futures for cell- penetrating peptides: how soon is now? Biochem. Soc. Trans., 35, 767–769. 69. Meade,B.R. and Dowdy,S.F. (2007) Exogenous siRNA delivery using peptide transduction domains/cell penetrating peptides. Adv. Drug Deliv. Rev., 59, 134–140. 70. Duchardt,F., Fotin-Mleczek,M., Schwarz,H., Fischer,R. and Brock,R. (2007) A comprehensive model for the cellular uptake of cationic cell-penetrating peptides. Traﬃc, 8, 848–866.