GLB1 and GM1 gangliosidosis: Collectively, our gene therapy studies in GM1 gangliosidosis patient cells are in agreement with Martin et al. (18), suggesting that GLB1 overexpression coincides with dose-dependent (Fig. 8 and Fig. S4) and time-dependent (Fig. S5) increases in early ER markers (PDI) and late ER markers (Grp78) of the unfolded protein response, as well as CHOP translocation, an indicator of prolonged ER stress.