(Invitrogen) was used for the negative control. Finally, the HIV vector encoding RAB27A shRNA was prepared by triple transfection of 293T cells with pCMVR8.2 packaging construct, pMD.G plasmid expressing VSV-G and pLenti6/BLOCK-iT- DESTTM-RAB27A-shRNA or pLenti6/BLOCK-iT-DESTTM - shRNA-Scramble Med GC. Administration of the lentiviral vector encoding RAB27A shRNA into cultured melanocytes NHEMs were seeded at a concentration of 2.06104/cm2 one day before the transfection. The melanocyte culture medium was replaced with fresh medium without PMA, followed by transfec- tion with the VSV-G-pseudotyped lentiviral vector encoding RAB27A shRNA or the Scrambled-RNA at a concentration of 3.06105 TUml21 in the presence of 6 mg/ml polybrene. On the following day, the transfection medium was replaced with fresh culture medium without PMA and cells were cultured for another 24 hr. Blasticidin (10 mg/ml) was then added and the medium References 1. Searle AG (1990) Comparative genetics of albinism. 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