In order to investigate the pathophysiological context between the occurrence of hematopoietic LSC-enriched progenitor cells (CD34+) with elevated levels of separase activity and disease progression, we have fractionized and comparatively analyzed separase activity–positive cells derived from diagnostic samples of a total of 88 CML patients and from 14 healthy control donors. Here, ESPL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.