NF-κB expression and dependence of ATMKO.CD3εKO B-cell lymphomas. (A) Immunofluorescence images showing staining for Rel (Alexa488), 4,6 diamidino-2-phenylindole (DAPI), or both in an ATMKO.CD3εKO B-cell tumor (left) and an ATMKO T-cell tumor (right) (original magnification ×40). Images were collected at room temperature using a Zeiss LSM510 META confocal microscope fitted with a 63× oil-immersion lens. (B) Quantification of mean nuclear/cytoplasmic intensity ratio for Rel staining shown for 2 B-cell tumors (closed symbols) and 2 T-cell tumors (open symbols) and calculated from 200 images collected for each tumor. Inhibition of ATMKO.CD3εKO B-cell tumors (closed symbols) and ATMKO T-cell tumors (open symbols) cocultured with the IKK inhibitors PS1145 (C) or MLN120B (D). (E) quantitative polymerase chain reaction detection of Malt1 expression in B-cell tumors (B1, B2, and B3) and lipopolysaccharide (LPS)-activated B cells. Data were collected on the ABI 9700 real-time polymerase chain reaction system (Applied Biosystems), and relative expression of Malt1 was determined using the 2^−ΔΔC_T method, normalized to β-actin expression, and presented as fold expression (± standard deviation) relative to LPS-activated B cells. This experiment is representative of 3 independent experiments for each sample. Inhibition of B-cell tumors (closed symbols) and T-cell tumors (open symbols) cocultured with the MALT1 inhibitors Z-VRPR-fmk (F) or M1-2 (G). For panels C-D and F-G, viable cells were counted and inhibition was calculated as described. Data are representative of 3 independent experiments examining survival of 4 to 6 B-cell tumors and 2 to 4 T-cell tumors in each experiment.