Los of Ext1/2 or Gpc5 only in the Sonic Hedgehog (Shh)-transporting cells suffices to enhance the Shh response. (A–H): Neuralized embryoid bodies, the bulk of which consists of the indicated genotype as well as 3% of Sim1:RFP cells, with (B, D, F, H) or without (A, C, E, G) 5% Shh-expressing cells. Images show tdTomato-expressing cells. (I): Quantification of (A)–(H). One-way analysis of variance (ANOVA) with post hoc Dunnett’s test; *, p < .05; ***, p < .001. (J–Q): Neuralized embryoid bodies, the bulk of which consists of the indicated genotype as well as 3% of Hb9:GFP cells, with (K, M, O, Q) or without (J, L, N, P) 3% Shh-expressing cells. Images show GFP-expressing cells. (R): Quantification of (J)–(Q). One-way ANOVA with post hoc Dunnett’s test; *, p < .05; **, p < .01; ***, p < .001. Scale bar is 100 μm.