Correction: Microtubule-induced nuclear envelope fluctuations control chromatin dynamics in <italic>Drosophila</italic> embryos

INTRODUCTION Although nuclei are often spherical, nuclear shape can change significantly between cell types and during cell differentiation or aging (Dauer and Worman, 2009). The nuclear envelope (NE) is a key determinant of nuclear morphology. The nuclear lamina, a meshwork underlying the inner nuclear membrane in metazoa, is crucial for the structural integrity of nuclei (Stuurman et al., 1998). Lamins, the major constituents of the lamina, not only support the structure of nuclei but also play important roles in transcription, replication or chromatin organization (Dechat et al., 2008). In most species there are two different types of lamins: a ubiquitously expressed B-type lamin, and one or more A-type lamins, which become only expressed when cells start to differentiate. A-type lamins control the mechanics of the NE and are responsible for the increased stiffness of nuclei in differentiated cells compared with stem cells (Pajerowski et al., 2007). Thus, nuclear mechanics must be tightly regulated. Changes in nuclear mechanics are accompanied by defects in gene expression and a distorted nuclear morphology (Dahl et al., 2008; Dauer and Worman, 2009; Lammerding et al., 2004). It is thus essential to decipher the mechanisms regulating nuclear mechanics and morphogenesis. By analogy to cell shape changes controlled by generators of forces and the mechanical response of the cortex, we sought to investigate the origins of nuclear deformations and to delineate active forces that shape nuclei and the mechanical properties of the NE.