PML and amyotrophic lateral sclerosis: To rule out whether the decrease in the number of PML-NBs observed in 66R overexpressing cells may be an artifact due to its high expression levels, we used iPSC lines expressing expanded (pathogenic) C9orf72 (referred to as C9-ALS) and gene-corrected non-expanded C9orf72 (referred to as GC) [48].