Effect of solubility of target protein on GFP fluorescence. A. Relative GFP fluorescence assay for GFP fusion proteins. B. Western blot of soluble fraction of GFP fusion proteins using anti-GFP antibody. Lane 1: MAP-GFP, Lane 2: GCSF-GFP, Lane 3: PTH-GFP, Lane 4: SAK-GFP. C. SDS-PAGE profile of the soluble fractions of the expressed fusion proteins followed by visualization under UV light. The induced cells expressing the fusion proteins were normalized to equal cell density and lysed by sonication. The soluble fractions were analyzed on SDS-PAGE followed by visualization upon UV exposure. Lane 1: MAP-GFP fusion (~55 kDa), lane 2: GCSF-GFP fusion protein (~41 kDa), lane 3: PTH-GFP fusion (~30 kDa), and lane 4: SAK-GFP fusion (~41 kDa). Arrows indicate the fusion proteins. Note the difference in fluorescence intensities of different fusion proteins directly reflecting the solubility of the target gene.