Asymmetrical signals with cytoplasmic fluors during bleb formation. The typical distribution of fluorescence intensity of cytoplasmic GFP along the axis indicated of a human neutrophil (a) and a Dictyostelium induced to bleb by ionophore and high extracellular Ca2+ (a′) (13 mM). (b) The fluorescence enhancement in the blebs, marked in the histogram “bl”, was similar to that observed with organelle-free cytoplasm at the leading edge or in phagocytic pseudopodia (marked “ps”) and was seen for both GFP and fluorescein (marked “GFP” and “fluor”, respectively [n = 17, 4, 8, and 5 for each column in order]). (c) The correlation between the increased fluorescence and the appearance of cytoplasmic blebs is shown in this time sequence in which the top panel shows fluorescein fluorescence and the bottom panel the corresponding phase-contrast images. The location of two blebs are marked by asterisks in the third image pair. Bars: (a) 8 µm; (c) 10 µm. The complete data for bleb formation and localized intensity increase are shown in Video 3 (available).