HSPA5 and frontotemporal dementia: Corroborating the qPCR data, no change in BiP and GRP75 protein levels was observed in 1-week-old iMNs, whereas all C9ORF72-ALS/FTD patient lines exhibited higher expression of the ER stress marker BiP and GRP75 compared with healthy control iMNs and isogenic control lines after 2 weeks (Fig. 1d) and 4 weeks of differentiation (Supplementary Fig. 2c, online resource).