HTR4 and amyotrophic lateral sclerosis: Among the gene ontology (GO) terms enriched, our analyses discovered the class of ‘adenylate cyclase modulating G proteins’ as an overrepresented category that included 10 related genes, Adcy2, Akap13, Chrm3, Gng2, Grm7, Grm8, Htr4, Pde4b, Rims2 and Rit2 (Fig. 6A), all of which up-produced DPpGCs under ALS conditions.