Transfected protoplast protein was isolated for Western blot assay. (A) Protoplasts were transfected with a 35S- soluble-modified GFP plasmid (MW: 26.7 kDa). Protoplast protein (lane 3 and 4) was extracted 16 hr later and the expressed proteins were analyzed by SDS-PAGE followed by Western blotting with anti-GFP antibody. Recombinant γGFP (Roche, Mannheim, Germany; lane 5-8, 26.8 kDa) was used for positive control and quantification. (B) Immunoblots were digitized and the intensity of the bands measured with Multi Gauge software (Fujifilm, Tokyo, Japan). About 0.1% of the total protein of protoplast was GFP. M: marker; PP*: transfected protoplast protein.