CRISPR/Cas9-mediated knockout of GRP78 
For lentiviral experiments, three sgRNA sequences targeting GRP78 were selected based on enrichment scores from the whole genome CRISPR screens and cloned into the lentiCRISPR v2 (Addgene plasmid no. 52961) according to the protocol provided by the Zhang Lab (Zuo et al., 2017). A complete list of CRISPR sequences can be found in Online Supplementary Table 4. Lentivirus was generated by co-transfecting HEK293T cells with lentiCRISPR v2, envelop plasmid pMD2.G (Addgene plasmid no. 12259), and packaging plasmid psPAX2 using Lipofectamine 2000 (Invitrogen, Carlsbad, CA, USA), Viral supernatants were collected 48 hours following transfection and used to infect HEK293T cells. Puromycin selection (3μM, HY-15695, MCE) was performed for 3 to 4 days establish the stable cell lines.