Recent research has shown that the inner nuclear membrane is a site for regulation of signal transduction from the plasma membrane to the nucleus. This has coincided with discoveries showing that mutations in extrinsic and intrinsic inner nuclear membrane proteins cause a variety of inherited diseases. In most instances, the mechanisms by which mutations in inner nuclear membrane proteins cause disease are not understood. In at least one case, however, an alteration in signal transduction appears to underlie disease pathogenesis. Copyright 2005 Wiley-Liss, Inc.