rab13 knockdown caused ISV defects. A, images of the vasculature in the trunk of Tg(flk1:EGFP) embryos injected by 12 ng each of a five-base mismatch control MO (Mis) or MOs targeting the ATG codon (MO1) and the exon 2-intron 2 splicing site (MO2). The embryos were fixed at 28 h postfertilization. B, quantification of the penetrance of the mismatch MO, of MO1, and of MO2 in groups of 44, 75, and 80 embryos, respectively.