Fig. 2. GFP is secreted by various cells including cancer cells. NIH 3T3, HEK-293, COS, MCF-7, A375 and HT-29 were transiently transfected with a plasmid encoding GFP. The day after transfection, the cells were labeled with [³⁵S]-methionine and chased in the presence of BFA. After 6 hours, the cell lysates (C) and media (M) were harvested and immunoprecipitated with anti-GFP antibodies. The washed immunoprecipitates were resolved by SDS-PAGE followed by fluorography. `% Sec.' denotes the percentage of GFP secreted by transfected cells.