Fig. 2. PLCβ1a and intracellular Ca²⁺. HeLa cells coexpressing YFP-C2 (A-C, green) and RFP-PLCβ1a (D-F, white, for higher contrast). Confocal images are shown at three different timepoints as indicated by the vertical lines in the graphs beneath (G-I). Addition of histamine (100 µM) is indicated by the arrow in G. Regions of interest were selected in the cytosol of three different cells. Graphs G, H and I show the normalized fluorescence intensity quantified from cells 1, 2 and 3 (as depicted in A), respectively. The green lines indicate the intensity of YFP-C2 in the regions of interest; the red lines indicate the intensity of RFP-PLCβ1a. Scale bar: 10 µm.