STAG1 and cancer: To establish ARTi as a method for target validation, we performed ARTi-based LOF experiments in cancer cell lines and xenograft models for three prominent oncology targets: EGFR and KRAS, which act as driving oncogenes in various cancer types (Hynes and MacDonald, 2009; Punekar et al., 2022), and STAG1, which has been identified as a synthetic lethal interaction with recurrent LOF mutations of STAG2 (Bailey et al., 2021; van der Lelij et al., 2020; Benedetti et al., 2014; van der Lelij et al., 2017).