CDK4 and amyotrophic lateral sclerosis: Cell cycle deregulation has been observed in multiple NDs, including AD, ALS and SMA.52,53 RB1/E2F1 pathway is also linked to cell fate decisions and the induction of apoptosis.51 To evaluate whether the upregulation of E2F1 pathway is associated with the cell death of p97R155H/+ MNs, In particular, we inhibited RB1/E2F1pathway through treatments with a FDA-approved CDK4/6 inhibitor, Abemaciclib.54,55 p97R155H/+ and iso p97R155H/+ MNs were treated with DMSO, 200 nM or 400 nM Abemaciclib from 8 dpm, and viable cells were determined by live cell staining every 6 days.