Induction of apoptosis by NR4A1 in GCB and ABC lymphoma cell lines. SuDHL4 and Karpas422 (Karpas) (GCB origin), and RI-1 and U2932 (ABC origin) lymphoma cells were transfected with empty pEZ-M61 vector (pEZ-M61-empty) or pEZ-M61 carrying the NR4A1 construct. (A) NR4A1 mRNA expression after NR4A1 transfection. Relative expression levels were in comparison with empty vector controls. Each bar represents the mean values of expression levels ± SD. (B-D). Apoptotic and cell growth assays of all 4 transfected lymphoma cell lines carrying the empty vector or the NR4A1 construct: cell growth analysis was performed by employing MTS assays (B). To evaluate the apoptotic effects of NR4A1 in aggressive lymphoma cells, Annexin V, by using the FACS methods with specific fluorophore-labeled peptides (C), and caspase 3/7 activity (D) were estimated. (E) mRNA expression levels of potential NR4A target genes of NR4A1 overexpressing lymphoma cells.