A method for increasing the transduction efficiency of cells cultured with a retrovirus comprising: culturing the cells and the retrovirus in a culture medium that comprises a compound that increases prostaglandin EP receptor signalling is disclosed. The cells are cultured with the retrovirus during, or prior to, culture with the compound that increases prostaglandin EP receptor signaling, and the compound that increases prostaglandin EP receptor signaling is selected from the group consisting of: PGA2 PGB2 PGD2 PGE1 PGE2 PGF2 PGI2 PGH2 PGJ2 and precursors, metabolites, derivatives and analogues thereof, or the compound that increases prostaglandin EP receptor signaling is selected from the group consisting of: 15d-PGJ2 delta12-PGJ2 2-hydroxyheptadecatrienoic acid (HHT) Thromboxane A2 Thromboxane B2 Iloprost Treprostinil Travoprost Carboprost tromethamine Tafluprost Latanoprost Bimatoprost Unoprostone isopropyl Cloprostenol Oestrophan Superphan Misoprostol Butaprost Linoleic Acid 13(s)-HODE LY171883 Mead Acid Eicosatrienoic Acid Epoxyeicosatrienoic Acid ONO-259 Cay1039 a PGE2 receptor agonist 16,16-dimethyl PGE2 19(R)-hydroxy PGE2 16,16-dimethyl PGE2 p-(p-acetamidobenzamido) phenyl ester 11-deoxy-16,16-dimethyl PGE2 9-deoxy-9-methylene-16,16-dimethyl PGE2 9-deoxy-9-methylene PGE2 Sulprostone PGE2serinol amide PGE2 methyl ester 16-phenyl tetranor PGE2 15(S)-15-methyl PGE2 15(R)-15-methyl PGE2 BIO 8-bromo-cAMP Forskolin Bapta-AM Fendiline Nicardipine Nifedipine Pimozide Strophanthidin Lanatoside L-Arg Sodium Nitroprusside Sodium Vanadate Bradykinin Mebeverine Flurandrenolide Atenolol Pindolol Gaboxadol Kynurenic Acid Hydralazine Thiabendazole Bicuclline Vesamicol Peruvoside Imipramine Chlorpropamide 1,5-Pentamethylenetetrazole 4-Aminopyridine Diazoxide Benfotiamine 12-Methoxydodecenoic acid N-Formyl-Met-Leu-Phe Gallamine IAA 94 and Chlorotrianisene, or the compound that increases prostaglandin EP receptor signaling is selected from the group consisting of: prostagland
