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Figure 3: Pancreatic cells in culture express cytosolic vesicles consistent with zymogens. Cells in culture were transfected with a plasmid containing a DNA GFP-amylase, and confocal laser scanning microscopy was employed to detect GFP-derived fluorescence. Viability of cells was not decreased under culture conditions. (A) A cytosolic homogeneous green fluorescence could be observed in cells transfected with wild GFP-encoding DNA. (A') Transmitted light image of cell shown in A. (B') Green fluorescence distribution, consistent with trapped fluorescent protein in cytosolic vesicles, could be observed in cells transfected with GFP-amylase-encoding DNA. (Bμ) Transmitted light image of cell shown in B. (transfection was performed after day 7 of cell culture; n = 4 independent preparations).