Ways of looking at calcium

What we understand about signalling pathways depends very much on the ways we can measure them. I review ways of measuring calcium and explore how cha nges in methods have led to new ways of thinking about calcium signals. I a lso suggest; how the ways we have of looking at calcium will influence the analysis of other signalling pathways that, until now, have not been studie d with the spatiotemporal precision available to those studying calcium sig nalling. (C) 1999. Wiley-Liss, Inc.