The previous edition of Transmembrane Signaling Protocols was publishedin 1998. Since then the human genome has been completely sequenced andnew methods have been developed for the use of microarrays and proteomicsto analyze global changes in gene expression and protein profiles. Theseadvances have increased our ability to understand transmembrane signalingprocesses in much greater detail. They have also simultaneously enhanced ourability to determine the role of a large number of newly identified molecules insignaling events. In addition, novel video microscopy methods have beendeveloped to image transmembrane signaling events in live cells in real time