Repression of PAX5-dependent transactivation by PAX5-ELN. (A) The plasmids luc-CD19 (5 μg), pcDNA3-PAX5 (1 μg), and the reference pRL-CMV (0.4 μg; transfection efficiency control) were transfected together into HeLa cells with increasing amounts of pcDNA3-PAX5-ELN. The luc-CD19 plasmid contains 3 copies of the high-affinity PAX5-binding site of CD19 upstream of the TATA box and the luciferase gene. Luciferase activity in 3 independent transfection experiments was normalized to the measured Renilla activities and are shown as average values relative to the basal activity observed with pcDNA3 alone (results are mean ± SD; Student t test; *P < .05, **P < .01 compared with DG75 transfected with pcDNA3-PAX5, without PAX5-ELN). (B) DG75 cells were transfected with pcDNA3-PAX5-ELN and pmaxGFP. GFP-positive cells were sorted 24 hours after transfection. CD19, BLK, BLNK, MB1, and LEF1 mRNA levels were evaluated by RQ-PCR (Results are mean ± SD; Student t test: *P < .05, **P < .01).