A validated panel of commercial antibodies for reliable detection of FET proteins.

The FET protein family comprises the highly conserved RNA-binding proteins FUS, EWS and TAF15 which are implicated in RNA metabolism and neurodegenerative diseases such as ALS and FTLD. Despite their structural similarity, reliable detection of individual FET proteins remains challenging due to antibody cross-reactivity and inconsistent localisation patterns reported in the literature. To address this, we systematically evaluated 23 commercially available antibodies for specificity and performance across western blotting, immunocytochemistry, and immunohistochemistry. Using single and double shRNA knockdowns in HeLa cells, we confirmed target engagement and identified antibodies which were specific as well as those with significant cross-reactivity. Immunofluorescence in rat primary neurons and HeLa cells showed antibody and cell type dependent variations in nuclear and cytoplasmic localisation; from these, we identified a subset that demonstrated high-quality, region-specific staining in postmortem human brain tissue. Our findings highlight substantial variability in antibody performance and underscore the need for rigorous validation to ensure reproducibility in FET protein research. We present a validated panel of antibodies suitable for diverse applications, providing a critical resource for studies of FET protein biology and pathology.