ROS1 and acute lymphoblastic leukemia: Thus, prioritizing the analysis of Tier 1–3 variants in the ALL borderland cohort, ROS1 S1109L, KRAS G12A, WT1 C303 *, STAT5B N642H, NOTCH2 E38K, and NOTCH2 C19W were screened for in the TARGET-ALL Phase II database to investigate their presence across a larger cohort.