Fig. 1 Confirmation of GFP expression by western blot analysis, and cardiac pathology. a, Lysates (30 µg) from ventricles of non-transgenic (NTG) and transgenic F1 heterozygotes of various lines were immunoblotted with monoclonal antibody against GFP. Arrow, 27-kDa protein corresponding to the size of GFP; arrowhead, unknown protein (41 kDa) that cross-reacts with antibody against GFP. Positions of molecule weight markers (kDa) are indicated at the left margin. b, Quantification of bands corresponding to the size of GFP by densitometry, plotted against the lowest expresser (line A). The expression of GFP in line C is twofold higher than that of line B. c and d, Transverse sections of non-transgenic (NTG; c) and transgenic (TG; d) hearts stained with hematoxylin and eosin, showing dilation of the right and left ventricular chambers in the transgenic heart. Scale bar represents 1 mm. e and f, Confocal analysis of frozen sections of non-transgenic (NTG; e) and transgenic (TG; f) hearts. GFP is expressed homogeneously in the cytoplasm and nuclei. Scale bar represents 40 µm. a b c d e f