(A) Quantification of EW midline crossing defects in the FraΔC screening background. Heterozygosity for RhoGAPp190 does not show a significant enhancement in crossing defects, however, RhoGAPp190 nulls do strongly enhance these defects (81%). pebble heterozygotes significantly suppressed these defects (10%). In addition, heterozygosity for rho1 or expression of a Rho1 dominant negative also suppresses the FraΔC phenotype. Data are represented as mean+SEM. n, number of embryos scored for each genotype. Significance was assessed by multiple comparisons using ANOVA (****p<0.0001, ***p<0.001, **p<0.01, *p<0.05). (B) Model of functional responses of Sema-1a reverse signaling through its downstream effectors.