(A) Expression of the W-CAT5′▵-1,580 construct in human hematopoietic cell lines. Transfections and CAT assays were performed as indicated in Materials and Methods. The amounts of extracts used in CAT assays were normalized based on the values of luciferase activity. PBL3-CAT was used as a negative control. (B) Comparison of the expression of W-CAT5′▵-1,580 in Jurkat cells and nonhematopoietic human cell lines. CAT activity is expressed as a percentage of the values obtained with the strong universal CAT vector, RSV-CAT, in each cell line.