Western blotting analysis for MALT1 in cell lines with 18q amplification. Equal amounts of protein extracts from various cell lines and a tonsil were subjected to Western blotting analysis for MALT1. The protein is expressed at a much higher level in SSK-41 and KHM-10B that have MALT1 gene amplification, than in Karpas 422, VAL, and tonsil.