Comparison of the transcriptional activities of the murine and human GPIIb promoter fragments, in murine (A) and human (B) cell lines.

Murine and human GPIIb promoters (−899/+33 and −813/+33, respectively) were cloned upstream of CAT gene in pBLCAT3 plasmid and transfected in different cell lines. The pRSVCAT plasmid containing the CAT gene driven by the RSV promoter was used as a positive control, and the promoter less pBLCAT3 plasmid was used to assess background level. In each assay, the pRSV-luciferase plasmid was cotransfected as an internal control of transfection. Cellular extracts were prepared 48 hours after transfection, and the CAT assays were normalized according to the luciferase activity of each extract. The CAT values were expressed relatively to the pBLCAT2 plasmid, containing the CAT gene driven by the ubiquitous TK promoter, which was taken as the 100% value to compare CAT activity between cell lines, and were presented in bar graph. Each value is the average of a number of independent experiments indicated in parentheses. (A) Transfection experiments in murine cell lines: LIN-175 (megakaryocytic), MEL (erythrocytic), and NIH-3T3 (fibroblastic). (B) Transfection experiments in human cell lines: HEL (megakaryocytic), K562 (erythrocytic), and HeLa (epithelial).