B. Frequency of ISV ectopic branching occurring at the HM (n=4 experiments; *P<0.05; one-way ANOVA with Bonferroni's correction). +/+, +/∆ and ∆/∆ represent Tg(kdrl:EGFP) rab13+/+, rab13+/∆3'UTR and rab13∆3'UTR /∆3'UTR embryos, respectively (B). 