Effect of mutations in the PU.1/Pip or μE3 site on CD20 promoter activity in B cells or T cells. The promoterless luciferase vector pGL3 basic, the wild-type CD20 promoter-luciferase gene construct (CD20-425-WT), the μE3 site mutated construct (CD20-425-μE3 Mut: CACCTG → AGCCGA) and the PU.1/Pip site-mutated construct (CD20-425-PU.1/Pip Mut: AAGAAGT → ACTCCGT) were transiently transfected into the B-cell lines, HS-Sultan, U266, and RPMI 8226, or the T-cell line, Jurkat. Experiments were performed in triplicates and repeated a minimum of three times. Mean and standard deviation values shown are derived from a representative experiment. Luciferase activities were normalized for transfection efficiency by cotransfection of a β-Gal control plasmid. Note the different scales used for the B-cell lines and Jurkat cells.