To determine whether the aggregation and toxicity of Htt exon 1 arise from SERF1a in cells, we co-expressed EGFP-tagged Htt exon 1 with 25Q (EGFP-Httex1-25Q) or 109Q (EGFP-Httex1-109Q) and SERF1a-myc or myc-only plasmids in mouse neuroblastoma Neuro-2A and subjected to fluorescence microscopy (Fig. 6a). Here, HTT is linked to neuroblastoma.