To test this, we knocked down Runx1 in multiple models—c-Kit+ bone marrow progenitors from Srsf2P95H and U2AF1S34F mice, K562 with SRSF2P95H and KO52 leukemia cells that naturally harbor SRSF2P95H—and measured CHK1 inhibitor sensitivity. This evidence concerns the gene KIT and leukemia.