ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: However, the existence of F-circBA1 was only detectable in 9/14 patients and not all BCR-ABL-positive patients with CML (Figure 1f and Supplementary Figure S3), which might be due to unknown causes such as low enrichment of F-circBA1 or differences in the in vivo microenvironment.