Using in situ proximity-ligation assay (PLA), a method that enables the exhibition of close protein–protein interaction (< 40 nm) while preserving the structural integrity of the cells [46], we found a tight association between PES1 and ILF3 in nuclei of paraffin sections, and the interaction was much stronger in ESCC tissues than non-tumor counterparts (Fig. 5F). The gene discussed is ILF3; the disease is neoplasm.