Confocal microscopy revealing the colocalisation of DAPI(a,d), VASA (c,d) and GFP (b,d) in iPS cell-derived cells exposed to RA in vitro. DAPI, 4′,6′-diamidino-2-phenylindole; GFP, green fluorescent protein; iPS, induced pluripotent stem; RA, retinoic acid; VASA, DEAD box protein 4.