ErbB4 could also mainly contribute to downstream signaling pathways phosphoinositide 3-kinase (PI3K)/Akt serine/threonine kinase (Akt) pathway activation (pathway ID# mmu04012), which had been tested for the possible involvement of its toxic action in ALS (Codeluppi et al., 2009). This evidence concerns the gene MARK2 and amyotrophic lateral sclerosis.