ISL1 and amyotrophic lateral sclerosis: Analysis of the expression of the specific markers OLIG2, HB9, ISL1 and CHAT in WT I and ALS iPSCs suggested that there is no impairment of MN differentiation in mutated lines (Fig. 2C,D and supplementary material Fig. S2C), as previously described for SOD1 and other TDP-43 mutants (Dimos et al., 2008; Bilican et al., 2012; Egawa et al., 2012).