In agreement with the 2008 study by Martin et al. (18), we observed a direct correlation between chronic GLB1 transcriptional overexpression in GM1 gangliosidosis patient cells and activation of an unfolded protein response, with dose-dependent accumulation of precursor β-gal coinciding with increasing levels of precursor PDI protein being detected in all three GM1 gangliosidosis patient fibroblast lines after 4 days of chronic GLB1 overexpression (Fig. S4). The gene discussed is GLB1; the disease is GM1 gangliosidosis.