PCBP1 joins the regulatory network of the endothelial-to-hematopoietic transition.

Ji and colleagues show that endothelial deletion of PCBP1, a multifunctional nucleic-acid-binding protein, reduces intra-arterial hematopoietic cluster formation and impairs subsequent hematopoietic development. These findings identify PCBP1 as a new regulator of early definitive hematopoiesis while leaving its underlying molecular mechanism unresolved.