Fig. 4. Six3 and Irx3 alter the regional responses to Shh. HH21 dissected brains normal (A,C,F), Irx3- (B,D,E), Six3- (G) and Six3 and Shh-misexpressed (H), were in situ hybridized for Nkx2.1 (E-H) or Nkx6.1 (A,B), or immunostained for Hnf3ß (C,D). Ectopic expression of Nkx2.1, Nkx6.1 and Hnf3ß, and the repression of Nkx2.1, are indicated by arrowheads (B,D,G,H) and an arrow (E), respectively. The sites of transgene expression were detected by GFP fluorescence (B',D',E',G',H'). Bars, 0.5 mm.