Cell-to-cell contact and extracellular matrix.

The topics discussed in this overview only scratch the surface of the contents of this issue, and necessarily reflect only some of the highlights that can be gleaned from the articles. The reader will learn a great deal more from this issue, which contains a particularly rich selection of very current topics, in both the traditional and new areas in the field. There continues to be remarkable progress towards understanding the mechanisms by which the different systems of cell-cell and cell-matrix contacts establish and regulate physical adhesive interactions and mediate transmembrane signaling processes in various tissues.