PCNA and chronic myelogenous leukemia, BCR-ABL1 positive: Consistent with previous findings that YB-1 regulates PCNA, epidermal growth factor (EGF), and DNA topoisomerase II α (TOPO IIα)44–46, YB-1 knockdown reduces the mRNA expression of PCNA and TOPO IIα (Fig. 6g and Supplementary Fig. 6b), indicating YB-1 is involved in DNA damage response in CML cells.