Defective Nodal and Cerl2 expression in the Arl13bhnn mutant node underlie its heterotaxia

► We examine left-right axis specification in Arl13bhnn mutants. ► Nodal expression is delayed in the lateral plate mesoderm. ► Nodal expression loses asymmetry in the mutant node. ► Cerl2 is not down regulated in the mutant node.