title: Waddington's valleys and Captain Cook's islands.
abstract: Somatic reprogramming has relied heavily on theoretical models that view differentiation in terms of developmental branch point decisions. Recent studies in Cell now reveal a dominant role of the microenvironment in shaping epigenetic identity of macrophages, thus providing support for alternative models of cell fate acquisition.
authors.affiliation: Centre d'Immunologie de Marseille-Luminy (CIML), Aix-Marseille Université UM2, Campus de Luminy, Case 906, 13288 Marseille Cedex 09, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1104, Marseille, France; Centre National de la Recherche Scientifique (CNRS), UMR7280, Marseille, France; Max-Delbrück-Centrum für Molekulare Medizin (MDC), Robert-Rössle-Strasse 10, 13125 Berlin, Germany. Electronic address: sieweke@ciml.univ-mrs.fr.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Sieweke