E. In situ proximity ligation assays (PLA) using antibodies against BRG1, ARID1A, DDIT3 and C-terminal parts of normal FUS show protein complexes containing FUS/BRG1, FUS/ARID1A, FUS-DDIT3/BRG1 and FUS-DDIT3/ARID1A as red fluorescent spots in nuclei of MLS cell lines 2645-94 and 402-91. C-terminal parts of FUS are not present in the FUS-DDIT3 fusion protein and normal DDIT3 is not expressed in these cell lines. Merged images also include DAPI nuclear counterstain in blue. Combinations of primary antibodies are used to detect interactions (left panel). In control experiments (right panel), one primary antibody is omitted to evaluate the background fluorescent signals. Scale bars = 10 μm. 