Because the catalytic subunit of the NADPH oxidase complex, CYBB (also referred to as NOX2 or gp91phox), is a PU.1 target (Fig. 1a), we quantified the respiratory burst capacity in Eμ-myc;bcl2 lymphoma cells using a p-nitroblue tetrazolium (NBT) reduction assay58. Here, SPI1 is linked to lymphoma.