Gouti, Briscoe, Gavalas 863 Figure 3. Expression of Hoxb1 represses the expression of DV markers. Detection of Pax3 ([D–F], [J–L]), Pax7 ([A–C], [G–I]), Nkx6-1 (M– O), Isl1 (P–R), Pax2 (AG–AI), and MNR2 (AJ–AL) by immunoﬂuorescence as well as detection of Bmp4 (M–O), Bmp7 (P–R), Wnt1 (S–U), and Wnt3A (V–X) expression by in situ hybridization on transverse sections of neural tubes 12h PE (A–F), 24h PE ([G–O], [S–AF]), and 48h PE ([P–R], [AG–AL]). Expression of Hoxb1 represses expression of the dorsal markers Pax7 (arrowheads in [B], [H]) and Pax3 (arrowheads in [K]) at 12 (A–C) and 24h PE (G–I), respectively. Consistent with a cell fate switch cells electroporated with Hoxb1 cease to express the dorsal signaling molecules Bmp4 (arrowhead in [T]), Bmp7 (arrowheads in [W]), Wnt1 (arrowheads in [AB]), and Wnt3A (arrowheads in AE). Expres- sion of Hoxb1 also represses expression of the medial marker Pax2 ([AG–AI], arrowheads in [AH]) and the ventral markers Nkx6-1 ([M–O], arrowhead in [N]), Isl1 ([P–R], arrowheads in [Q]) and NMR2 ([AJ–AL], arrowheads in [AK]) at 24h PE (M–O) and 48h PE ([P–R], [AG– AL]). Abbreviations: GFP, green ﬂuorescent protein; PE, postelectroporation. www.StemCells.com