Updated project metadata. Updated publication reference for PubMed record(s): 31741433. Human non-small-cell lung cancers (NSCLCs) harboring activating mutations in epidermal growth factor receptor (EGFR) frequently respond to EGFR tyrosine kinase inhibitors (TKIs), such as erlotinib and gefitinib. However, the responses are not durable, and the magnitude of tumor regression is variable, suggesting the existence of genetic modifiers of EGFR dependency in EGFR-mutant NSCLCs. Here, we applied a genome-wide CRISPR-Cas9 screening to identify genetic determinants of EGFR TKI sensitivity and uncovered both known and putative candidates. Specifically, we show that knockout of RIC8A, a guanine nucleotide exchange factor (GEF) essential for G-alpha protein activation, enhanced EGFR TKI-induced cell death and prevented acquired resistance. Mechanistically, we demonstrate that RIC8A is a potent positive regulator of the pro-survival YAP signaling pathway, activation of which rescued the EGFR TKI sensitizing phenotype resulting from RIC8A knockout. We also show that knockout of ARIH2, or other components in the Cullin-5 E3 ubiquitin ligase complex, conferred resistance to EGFR inhibition, in part by promoting nascent protein synthesis through METAP2. Together, these data uncover a spectrum of previously unidentified regulators of EGFR TKI sensitivity in EGFR-mutant NSCLC cells, providing insights into the heterogeneity of EGFR TKI treatment responses in EGFR-mutant NSCLCs.