Subcellular localization of BCL10 cotransfected with MALT1(1-380) and API2-MALT1. COS7 cells (2 × 10⁴) were transfected with the following expression vectors: (A) myc-BCL10 and flag-MALT1(1-380), a mixture of 0.02 μg pcDNA3-myc-BCL10 and 0.18 μg pcDNA3-flag-MALT1(1-380) with or without 4 ng/mL LMB; (B) myc-BCL10 and flag-API2-MALT1, a mixture of 0.02 μg pcDNA3-myc-BCL10 and 0.18 μg pcDNA3-flag-API2-MALT1 without 4 ng/mL LMB. For each experiment, the cells were processed as described in Figure 2 before fixation. For the first antibodies, mouse anti-flag antibody and rabbit anti-human BCL10 antibody were used, and for the second antibodies, fluorescein goat anti-mouse IgG and Alexa Fluor 546 goat anti-rabbit IgG. Below the immunofluorescence images, the relative proportions of cells with specific subcellular localization patterns are shown. C indicates cytoplasm only; C > N, predominantly cytoplasm; C = N, evenly distributed between cytoplasm and nuclei; C < N, predominantly nuclei. (C) COS7 cells (1 × 10⁵) were transfected with NF-κB-dependent luciferase reporter vector, an internal control vector (phRL SV40), and the following expression vectors: for control, pcDNA3-myc; for MALT1, pcDNA3-MALT1-flag; for BCL10, pcDNA3-myc-BCL10; for MALT1 + BCL10, pcDNA3-MALT1-flag and pcDNA3-myc-BCL10. Treatment with 4 ng/mL LMB was performed 18 hours after transfection, and luciferase activity was measured using the method of the Dual-Luciferase Reporter Assay System (Promega) 24 hours after transfection. The figure shows the results of representative experiments performed in triplicate. Error bars indicate standard deviation