LGALS4 and amyotrophic lateral sclerosis: To this end, we employed an established D. melanogaster UAS-Gal4 expression system to target expression of human wild-type TDP-43 and ALS-associated mutant TDP-43Q331K (hTDP-43WT and hTDP-43Q331K) [17] in retinal (driven by the GMR promotor) or motor (driven by the D42 promotor) neurons with or without knocking down of endogenous RACK1 by RACK1-RNAi co-expression (Fig. 9a), with mCherry-RNAi serving as a control.