To examine whether HDAC inhibitors would preserve DNA repair, we utilized the experimental model, in which recruitment of FUS-GFP to laser irradiation sites (linear cuts) in the nucleus (illustrated in the movie accompanying Fig. 9a), is measured in iPSC-derived motor neurons CRISPR/Cas9-engineered to express FUSWT-GFP or the ALS-linked mutant FUSP525L-GFP (Naumann et al. 2018). Here, HDAC9 is linked to amyotrophic lateral sclerosis.