Case12 and Case16 in living cells. a,b. Typical responses of HeLa cells expressing Case12 (a) and Case16 (b) to Ca2+ ionophore A23187. c,d. HeLa cells expressing Case12 are shown before (b) and after (c) ionophore addition. e-h. Fluorescence changes of M21 (human Melanoma-derived) cells expressing Case12 in response to 100 μM ATP. Images were captured every 0.294 sec on the confocal microscope. e,f. Individual responses of two selected cells within 400 s after ATP addition. g,h. The same cells, first 60 s of response. i. PC12 cells response to 500 uM carbachol (CCH). j. PC12 cells response to 30 mM KCl. For i and j first and second arrows indicate the moments of a compound addition and of washing start, respectively.