Proinsulin: Much more than a hormone precursor in development

We thank E.J. de la Rosa and A. Mansilla for critical reading. Studies in the laboratory were funded by Red de Grupos RGDM G03/212 from the Instituto de Salud Carlos III (Spain), BMC 2001–2132 from the Spanish Ministry of Education and Science (MEC) to F. de P. and CAM GR/SAL/0647/2004 to C.H-S. The Ramon y Cajal contract to C.H-S. and the fellowship to O.B. were awarded by the MECPeer Reviewe